Welcome to the forum, Sarah!
To hand pollinate tomatoes, use a q-tip or a small artist's-type paint brush. Gently swirl it around inside each blossom. Each flower of a tomato plant has both male and female characteristics, so they are self-fertile. All you need to do is get a few grains of pollen from the stamen onto the pistil.
"Isn't it enough to see that a garden is beautiful without having to believe that there are fairies at the bottom of it too?" - Douglas Adams