How to create a private game in csgo for aim training?
If you want to load one of the Steam Workshop aim maps, it's the wrong forum. Look for "how to start aim map csgo" in your favourite search engine.
If you want to create such an application in Snap, then search for "aim trainer" on snap.berkeley.edu. You can look inside those projects and make improvements.
This is the wrong Forum to post this. Post it in the CS:GO Steam Community page.