Problems on creating a game

Sorry guys, I'm first time being on FAF.

When I tried to create a game just for some causal versus AI mode, I don't have any UI or SIM mod, used the map generator to create a new random map, but after I press create, , it shows me I have to open some kind of file and I don't know which file should I open. I don't know what to do.

And it gives me this error message " The specified location does not cotain a valid supreme commander.exe and is therefore is no vaild Forged alliance installation"

I had buy the forged alliance game on stream but I don't have any supreme commander.exe

I am sorry being an idiot in software but I hope someone can teach me what should I do.

Many thanks

Download and start Supreme Commander:Forged Alliance from Steam, then you'll be able to create a game