Do check out Stick's posts. Lots of important informaiton for anyone new to routers.
To start with, you will want to check the router to see if you have collet nuts, which screw onto the router's shaft and when tightened, hold the bit in place. If you don't find it or them, you can't use the router until you find or buy them. Some older routers of that brand are very hard to find parts for, so that's your first task. If you only have one collet, you'll be limited to either that size shank bits, until you order and buy both sizes. Hopefully, your dad kept these around.
It's likely you'll be nervous when using the router, that's as it should be. You want to keep control because the bit is spinning around 20,000 rpm and can skin a section of your leg or whatever it hits before you can react. So I suggest you watch videos of using a router on YouTube, and see if you can find a book on routing for some guidance. You can find used books on using the router on Amazon. Don't mean to scare you off, just to treat the tool with great respect, like any power tool, it does great work, but spinning blades and bits demand cautious use.
A good place to start is making roundovers on sharp edged boards. These are done with a roundover bit. Almost all of us use these and have a set on hand. Sets usually include a 1/4, 1/2 and 3/4 inch roundover bit. How you use them depends on what kind of base you have on the router. A fixed base is pretty common, but you could also have a plunge base. You press on the handles on a plunge base to lower the bit into your work piece. Or you can lock the plunge base and use it as if it were a fixed base. That's enough to start with.
The router is a really versatile tool and you can do amazing things with it. And you can count on guidance from the folks here.
The more I do, the less I accomplish.