My wife and I have three. An Arabian, and Belgian/quarter horse cross (these two are my wife's). I have a mustang/quarter horse cross. We ride them in the mountains all summer, and are hoping to use the big boy for packing this year. My wife is the expert, and I just do what she tells me. None of our horses had much trainig before we got them. As a matter of fact, she broke hers herself. It's a lot of work and takes a lot of time to do right. She really knows her stuff when it comes to horses Oh, Oh, she just asked me what I was doing, and when I told her about your situation, she said you may be getting into something over your head. (no offense) She thinks you'd be better off getting horses with more experience and training. I can tell you this, if I didn't have her training all three horses and ME, I'd never have been able to start riding. But there are lots of sources of info out there - magazines, websites, DVDs, etc. They are great animals and great fun. Good luck.
Here's a pic of Oaky and me at about 9,000 - a tough climb!