Trying to host games with a DSL connection

I was trying to play StarCraft the other night as well as some other games and I noticed I cannot host a game.. I was told this might have something to do with specific port settings..

I don't have a router or anything, I have just a basic High Speed DSL connection..

My question is.. Do you think these port settings really are the problem? and if so how do I adjust them, if I even can.

Sorry if this is kinda vague, I just don't know a lot about this or why it's happening.

 

What's the exact error saying you can't host a game?

What's the DSL modem make & model?