Well at least you are doing your first job on an inexpensive rifle. Do you know where to mount the base? When you know the spot to put it you can put thin double sided tape on the base and use the base for your drill guide. You know that it has to be very straight and in-line with the rifle bore. If it is even a little off you will most likely not have enough adjustment in the scope to sight it in. OK enough scare talk. It always good to see someone do things for themselves. So have at it. Do you have the correct drill and tap? Most bases use 6-48 screws(#31 drill) or 8-40 screws(#28 drill). I have both and if you bring your rifle over you can use my drill press.
Just walking on the edge of of my grave.