Help learning Bioinformatics

I saw link on the side but I don't think any of it pertains to what I am learning. I am taking a class but I am having a very hard time understanding what the professor or his notes are trying to say. We are learning about BLAST, CDART, PSSMs etc. It all makes no sense to me as I am in biology and not bioinformatics. Does anyone know a good tool to use to learn these better?