Many of us going have never won a tournament and probably don't expect to win this one. That shouldn't stop you from entering, however, because you get a lot of valuable experience from tournament matches, experience of a different kind than you get playing friendlies. In tourney matches certain things come into play a lot more than in friendlies, like counterpicking, being able to switch characters between games, more camping / CGing / other assorted "cheap" tactics, and in general a higher level of pressure.
So just go, enter the tourney, but don't beat yourself up if you lose all your pool matches (which you most likely will). Just try to learn from the experience and do a little better next time.