This might not be the best time to try to learn how to true up a wheel. But if you really want to try, Sheldon Brown website is a good go-to site for most bicycle mechanical things. It sounds to me like your wheel is useable, so carefully weigh the chance that you might make things worse before you try it.
http://sheldonbrown.com/tooltips/truing.htmlI suggest you only try to turn the spokes maybe a quarter turn at a time. Your rim is probably damaged enough that it will need replacement, so you should not try to get it perfect, instead just get it good enough until you get to a place where you can get a new wheel or new rim.
Each time you adjust a spoke, that pulls the rim to one side at the location of the spoke nipple, but it also pulls the rim to the other side on the other side of the wheel, so minute adjustments are best because you may need to compensate on the other side of the wheel.
From your description, I have no idea if your rack is bent or if your fork blade is out of alignment, or both.