First of all, if you're a console modder, and you've created your own mods, then you would've used IDA to poke around XEXs with.
Basically, PC is the same. Except, instead of using IDA, we use Cheat Engine.
Open Cheat Engine and select your game's process. Bam, you have a similar environment to console modding/finding offsets.
You can now use C# to create your mods. Or, you could learn C++ and write .dlls which then can be injected.