Steam API for Dota2 and CS2

[Savvy]

Hello, i do not understand how to use API for dota2 and cs2, do steam has good documentation about how to use it. I always encounter in errors such as "Bad Request" where i should guess what to put in missing field or Forbidden "Access is denied. Retrying will not help. Please verify your <pre>key=</pre> parameter." - i check 100 times, it is correct. Some of the calls working and return code 200, but i have to guess what fields - what means it's very hard.

I'm trying this docs https://steamapi.xpaw.me/ - but it's uncompleted ((