Welcome. You'll probably have a pretty easy time getting back up to speed. First thing to me about routers is making a table to mount it under. Many of the things you can do with a router are more safely done on a table. These can be pretty simple, just two layers of very flat ply. You'll need a mounting plate that is drilled for your router. You can order one from many sources, Kreg being one. Be sure you get one that has a twist lock insert system, the old ones use 3 tiny bolts that quickly go AWOL.
You will remove the plastic base on the rounter to put it on the plate. Cut a hole in the top layer of your ply just a hair larger than the plate (Put painters tape on the bottom, then draw the outline there if you are going to cut it out with a jig saw. This reduces tearout. Use a pencil to outline the plate, then if you have a forstner bit set, or a standard drill bit, find one the same radius as the corners of the plate. Drill the corners out then cut the straight. Cut first tight to the line, and use a little sand paper to smooth the opening. Lay this cut out top on the second layer and mark an opening a half inch smaller all round to form a lip on which your plate will sit. Glue the two pieces together and clamp them or use short screws to secure them together tightly. You want to spread the glue as evenly as possible using a plastic card so it isn't lumpy.
Kreg makes some corner mounted leveling screws that make it easy to level the mounting plate with the ply top. You don't want any edge of the plate or top to catch your workpiece.
You will remove the plastic bottom on the router before you mount it to the plate. Keep that plastic bottom plate for when you use the router freehand. Here are a couple of pictures of the plate and leveling gadgets.
I strongly suggest you find a book on routers. They are so versatile that you can use them for far more than you'd think. A used book on routers is available on Amazon for a few bucks. You'll wind up making a few shop built jigs. These allow you to do all kinds of projects, from making boxes to making table tops.
A router table needs a fence. This can be very simple, but it needs to be really straight/flat. You could use a very flaty 2x, but I think is you have a well setup saw, you can make it with two very flat 3/4 pieces, glued into an L shape, with an opening on the face large enough for your biggest bit to fit into. Use some SQUARE, 90 degree cut, pieces to back up the fence so it stays square. A tall fence can be very handy, so consider using a 6 inch or so wide piece for the face. The L shape allows you to clamp the fence in place, so it should be maybe 4-6 inches longer than the table is wide. I prefer a larger table size, 20 inches by 36 inches would be my choice.
You can use almost anything for a base, including laying it across a couple of saw horses. You can stow it vertically if space is tight.
There are a lot of details on using a router that you can find in a book on the topic. Do a little research before you start. One important thing has to do with direction of travel of the workpiece. Below is a diagram explaining climbing cuts, which cause a lot of tearout. Has to do with the direction of rotation of the bit in relation to the workpiece.
Be careful about youtube videos, many of them show dangerous and improper use. You don't want that bit to hit you while turning at 20,000 RPM.
