Practice makes perfect! Try drawing a design on your fabric and then go over it and over it without thread. Then thread your machine and try it with thread - in a contrasting color so you can really see the stitches. I like to practice "drawing" things like stars, hearts, waves, flowers, etc. On my first quilt on my frame I drew all sorts of things in the quilting and even wrote my son's name. Maybe one day he'll actually find his name in it!
The last quilt I did - a baby quilt last month - I printed out a design and laid it in front of my needle and using my arms to guide the machine, I kept my eyes on the pattern so I could try to follow it. It came out pretty good.
Good luck and just don't give up!