i think u can

I'm not sure what you mean. You don't know what game the key is for? In that case, you can't make a giveaway.

Uhh, not through the SG giveaway system, but you can pick random people in the forum and randomly pick a key from a list you have to give to the winner if you really want to do things that way, I suppose.

I have site where you can buy steam games and others and they have somthing that they call randomly generated steam key so you have chance to get one of 150 possible games for lower price so i want to create a giveaway for that randomly generated key but dont know if i can or not

You'll need to specify the game that you are creating a giveaway for. If you don't know what your randomly generated steam key is for, then you can't create a giveaway.

1 buy the random game key

2 probably when they send you the key it will be with game name

3 make giveaway for this :D

Try to activate the game, if you already have it, it won't activate and it will say what game it is, then you can make a giveaway.