Try to relax a bit. Just starting out you have to develope the muscles that are used to shoot. It takes time, and if you feel you are getting tied then stop shooting for a while. Concentrate on the spot you want to hit and let the pin float. It is physically impossible to hold perfectly still, and the harder you try the worse it gets.

Not knowing your stature or setup I'll add that not being able to hold steady also can be a sign of too long a drawlength, which about 80% of the shooters have. To get an idea of correct drawlength, you can measure your wingspan from fingertip to fingertip. Divide this figure by 2.5. This will give a quick reference as to what you should be shooting. And keep the weight down. If you're shooting anything around 50lbs you have enough for deer. Shoot this lower weight so you can shoot more and perfect your form and develope those muscles that do the work.

Lastly, if you live anywhere near an archery club I'd suggest joining. There are often people around who can help you out with form or equipment problems. And if you want the right advice you look for some of the better target shooters in the area.