Brynn, to adjust the presser bar to the correct height, do the following:
1) Raise the presser bar, and loosen up the thumbscrew on top of the presser bar, to the point where the spring is not exerting any downward pressure, which would make it difficult to adjust.
2) Remove the faceplate. Then, using a screwdriver with the correctly-sized bit, loosen up the single screw that holds the presser bar in its bracket. Loosen it just enough that you can easily slide the presser bar up and down.
3) Turn the handwheel until the feed dogs are completely submerged under the needle plate.
4) Get a deck of playing cards and cut it exactly in half. No, this isn't a magic trick. When raised, the presser bar should be 19/64 of an inch from the needleplate; not an easy distance to eyeball, but I've found exactly half a deck of playing cards--that's 26 cards--is just about 19/64" thick.
5) Stick the half-deck of cards under the presser foot, and adjust the presser bar until the foot is resting firmly on the cards. The tricky part will be keeping the presser foot parallel with the feed dogs while you do this. Once you've got it correctly positioned, tighten up the screw in the bracket.
Now you should be good to go. Might take you a few tries to get the foot parallel with the 'dogs.
hope that helps,