Finding offsets is a generic thing not specific to CSGO. If you want to find your Local Entity, use Cheat Engine to find your player's position or something unique to your player, and follow one of the many tutorials online for finding pointers with Cheat Engine. This is where the offsets come from. If you want to learn about how the offsets are updated automatically after they are already found, you should search for 'signature scanning'. I believe there are some nice tutorials on this forum. The best implementation of sig scanning I have seen so far is in Y3t1y3t's offset dumper. You can google him to find his github repository.