Welcome Raquel. Try here for starters:
http://www.medicalbillinglive.com/medical-billing-products.shtmlAs you read through the posts at the this site, you should come to the conclusion that, rather than being here to stay, this business is going through a serious transition, as is the rest of the medical field.
The government's encouragement for the medical field to transition to Electronic Medical Records, and the fact that much/most of these EMRs are being offered in the cloud, is leading to some irreversable changes. That doesn't mean someone just starting out can't make it. But it complicates the process - since those offering the EMRs in the cloud are also offering billing services as well. That makes a certain amount of sense, since using an EMR forces the doctor to type the codes into the computer. Since the codes are already in some company's EMR, it doesn't take much further effort for that company's worker-bees to send those codes off to an electronic clearing house.
Given that doctors are in the middle of figuring out how to respond to the government's "encouragement" to start using EMR's, you may not get the response you are looking for as a newbie just starting out. You might consider going to work for a hospital or large doctors group, in their billing department, just to get some experience.