You are going to have to learn a few things if you want to be able to use a CNC. If you are unwilling to learn, the machine will never be more than a paperweight. No matter how old you are, if you are willing to learn, you should be able to get there. Admitting that you are not sure of what you are doing was the first step on your road to success.
I can’t teach you everything you need to know, but I’ll provide an outline. You may already know some or all of what I’m going to explain, but I’m going to give the basics for other readers who may also be interested in what it takes, or just starting out themselves.
First you have to understand the CNC workflow. You need to draw something you want cut or carved, on your computer. Inkscape is simply a drawing program, one that is free, and vector based, and used by many for those reasons. It can export, or save, files in “DXF” format, which was developed many years ago and is/was used by autocad, and is simply a file format used by a very wide variety of other software programs, and one way to exchange drawing information between them.
Next in the workflow is to convert the drawing into something your CNC control program can understand. This is probably what makercam does, reading the saved “DXF” file, and converting it into a g-code file. This step is not automatic - you need to determine HOW to make the conversion. For example, if you draw a simple box, do you want the router bit to cut inside that line, along that line, or outside that line? How deep? How fast? With what bit diameter? Being able to make these decisions may be the hardest skill to learn. This information is then saved as a g-code file.
Once you have your g-code file (it is a simple text file with very low level step by instructions on how to make your design), it is then time for the CNC controller to take over. The CNC controller can take many forms. In some machines, like the small piranha and shark machines, and even the newer powermatic CNC, it is a small, preconfigured box with very limited user interface. In probably the majority of hobbyist machines, it is a pc running some type of CNC controller software. Mach3 is one such program, there are quite a few others such as UCCCNC, LinuxCNC, and WinCNC. The CNC controller, whatever its form, interprets the g-code file, and provides the commands to the motors that move the CNC. A simple g-code instruction “g0 x3 y4” might result in commands to 3 different motors, essentially saying “motor 0 turn clockwise 1 step, motor 1 turn counterclockwise 1 step, motor 2 turn clockwise 1 step” repeated thousands of times a second, with the commands coordinated so the machine accelerates to a certain speed and moves in a straight line to position x=3, y=4 in whatever units (inches or mm) you are working in.
This controller program also provide other functionality, such as being able to manually command the CNC to move around (“jog”). For example, before running a g-code file, you may need to manually move the bit to a corner of your workpiece, and set that point as the “zero” point for your cut.
It is my understanding that a lot of the cheap Chinese 3040 and similar routers come either with an older pirated version of Mach3 or just the demo version. A current, valid demo version is freely downloadable from Newfangled Solutions (the developers) at their website:
Newfangled Solutions » CNC Software Home of Mach3. A license for this software costs $175 and if you received a license code with your router it may not not be legitimate. Mach3 will run in demo mode, but there is either a limitation on how long it will run (5 minutes at a time) or how many lines of g-code it will run. Buying a license code removes the time or g-code limits and converts the demo to a fully operational version.
One way of configuring Mach3 (by the way, Mach 3 is no longer under active development, its replacement Mach4 is available, both are useable) is by installing an XML file that contains all the configuration info required to set up Mach3 for your router. Look carefully for a file ending in .xml on the disk you received. Tutorials and instructions on how to install Mach3 and how to install the XML file are available at the site listed above. I would download Mach 3 from there and not use the one that came with your CNC, but would use the XML file if one was provided.
If the seller did not provide an XML file for Mach3, you are in for a lot more work, since you will need to manually configure it. Again, information on how to do this is provided at the Newfangled web site, but you will need to know a lot about your machine, and the CNC hardware. I would contact the seller (open an eBay resolution if necessary) for documentation about the machine. Worst case is you may need to google info about the specific controller card and stepper motors to configure. As stated above, the controller needs to convert the g-code commands into specific commands to the hardware. To do this you need to configure very low level information such as which pins on the computer are are connected to which pins on the motor controller, and how many steps there are per inch, how fast (inches per second) the motors can move, how fast they can accelerate, what pins are connected to limit switches, are the switches normally open or normally closed, etc. Mach3 stores all this information in a single XML file that it loads every time you launch the program. Generally when you buy a commercial or kit CNC, the manufacturer provides this as a preconfigured file in XML format.
There are members on this forum that can help you, but you will need to ask specific questions, telling about what you know and where you are stuck. Tell us what you have tried and where you are. Can you get the machine to power up? Have you connected the machine to your computer? How (parallel port or usb). Is Mach3 loaded? Have you loaded an XML configuration file?
I doubt you are “stupid”. Maybe uneducated, but if you are willing to put in the work to learn, I am sure the education will come.