How does Hammer know what game I'm making a map for?

Teflon

L1: Registered
Jul 22, 2016
1
0
Sorry if this has been asked before. I've searched everywhere and gotten no helpful information. I'm a complete noob to mapmaking, and every time I try to compile and run my map, Hammer opens up Source Filmmaker instead of Team Fortress 2, and just gives me the new session screen instead of even opening the map. Is it supposed to open in Source Filmmaker, or am I doing something wrong? Is it related to how I'm opening Hammer through clicking the Source Filmmaker button, then selecting SDK from the list that shows up, then selecting Hammer Editor from that list?