Nobody ever turned out beautiful flies the first time they sat at the vice. It takes patience, practice and perserverance.
It also doesnt hurt to have some instruction of technique. Lots of times local Trout Unlimited chapters have get togethers for members, where people get together and tie flies. You might check with your local chapter.
Also pick up a couple of good tying referrences. I am very fond of a well worn and much loved copy of "Trout Flies" by Dave Hughes.
Finally... Go find some bluegills and chuck that fly at them. After they've chewed it up and you've convinced yourself that it does indeed catch fish, go back to tying and after you've tied a couple thousand you'll see that it's not as insurmountable a task as you initially thought.