Undergoing colonoscopy in a week

I went to the doc ten days ago just to check out the cause of symptoms I had (and still have) like changes in my bowel movements, abdominal pain that I have and occasionally rectal bleeding. I also lost some weight lately and need some info about colonoscopy for I’m undergoing one in a week and am curious what to expect. What should I do to prepare myself for colonoscopy and what colonoscopy is anyway.

My brother had colon problem few years ago and had colon biopsy for he had an inflamed tissue removed from his colon and it turned out not to be that serious as we thought. So as much I’m familiar with it colonoscopy is a procedure which examines your entire large intestine with colonoscope which is large, flexible lighted tube that doc will insert in your rectum in order to see your colon from the inside. And this “scope” thing used to transmits the inside colon image on the monitor so the doc may see what he’s doing. This procedure won’t last longer than 30-60 minutes during which time you’ll be given some medications to be more comfortable while exam. And my brother said he doesn’t even remember the colonoscopy. I remember my brother saying that few times he felt mild cramping but then he’d take few slow deep breaths to make himself relax. And for the preparation you better go on 1-3 days diet avoiding food colorings. You’re allowed to have fat-free bouillon, fruit juice, water, plain coffee or tea and diet soda. And I remember my brother taking a laxative the night before colonoscopy.