First off, if your alias is your real name, that's not a good idea. You have no way to know who is watching.
Some resources for understanding the process:
MSAR: medical school admissions requirements. Any copy that's no more than a couple years old is fine. This should be available at your undergrad advising office or in the library.
Iserson's "Getting into Medical School: A Guide for the Perplexed" which is like having a parent who is a physician.
I have taken General Biology, General Chemistry, Anatomy and Physiology I and Microbiology. What other courses do I need to take?
Unfortunately, if these are the nursing prereqs, they are probably the "wrong" classes for premed. Med schools require a year each of the following:
General chemistry with labs
Organic chemistry with labs
Physics with labs
Biology with labs
Usually, more is required, but this depends on the school. (Edit: it depends on the med school, not the undergrad.) Typically there's a year of English, maybe some calculus, humanities, psychology, biochemistry or whatnot as an additional requirement. All this is in addition to finishing a bachelors degree (major does not matter).
See if your school has a premed advising web page. The courses aimed at premeds are the ones you need.
I don't suggest talking to the premed adviser, because he/she will look at your grades and try to talk you out of it. Seriously, you will need to figure out how to get A's in science classes that are a great deal more rigorous than what you've taken so far.
DO means Doctor of Osteopathic Medicine. It's a parallel physician training system to the system that produces MDs. DOs have the same practice rights as MDs (prescriptions, surgery, reimbursement, etc.). DO schools currently have lower averages for GPA and MCAT than MD schools.
Best of luck to you.