To the original poster:
As others have said here, focus on the BASICS first... learn anatomy and physiology, learn basic medical terminology (hint - many textbooks have lists of the basic terminology in one chapter, or in an index), learn normals - normal ranges of pulse and breathing for adult, child and infant.
You don't need to spend lots of money to get this information - as others have said, get used textbooks. Check ebay, or used bookstores, or buy from someone who took the course and decided it isn't for them. Search the internet - a good introductory site is www.emtb.com, and there are a number of others as well.
Don't try to cram too much into your brain at a time. You want to remember it for later, not just cram it in for now.
To Teen EMT:
When I saw your post regarding 'get a Littman' I knew you were going to get negative comments on that. A Littman does not make or break a practitioner - knowledge and skills do. As JPINFV stated earlier, it is important to know how to use it and recognise different heart sounds.
There are several threads on this site regarding stethoscope use - take a look, and read them with an open mind... there are a number of posters on here who have more years of experience than you have been alive, who are doctors, paramedics, respiratory techs, and have significantly more education than you or I. Use them to learn from, and to broaden your horizons.