actually the camshaft changes rotary motion to up and down motion with each of the cam lobes.This information is transferred to the valves via a rocker arm. some cams have cam followers(lifters) and push rods.some cams(overhead) do not use lifters.
The shape and size of the cams determine how much the valves open and how long they stay open and when this happens.Start with the basics like I originally said. Improve the exhaust system and the intake system first.As power increases you will learn whats next. Everything costs money,think awhile before buying.