what is the best language to code computer games and what's the best software to code it in?
That depends what sort of game you're making, how professional you want it to be, and what consoles you want it to run on. If you're on the computer, you can use something like Lua, or use something more advanced such as C++. Examples of games, Minecraft was done in Java, and CoD was done in C++.
Your first step should be to totally plan out your game, while things are bound to change during the development process, you need to have it completely planned out.
However, before you do that, learn to program, and learn to do it well. It doesn't matter what language you start with (although I'd recommend Java or C#, as they seem to be fairly common/easy starting languages), as you can really build a game in any language.