What info should I have to care for my dog in heat?

My one year old terrier-poodle mix is in heat. I do not want her to become pregnant. I need info about female dogs in heat (ie how long it lasts) and if I need to do anything special for her.

keep her inside

I have an 8 month Jack Russell that is currently in heat. My vet told me to expect her to be in heat for 3 weeks. One week coming into heat, 2 weeks being in heat, and the third week coming out of heat. During this time they may bleed for 6 days or more. My dog has bled the entire 3 weeks almost. Do not worry, they eat very little and sleep a lot. My dog did wear the panties where you can put liners in them. I got hers at Pet Smart and my dog did not mind them. I would put old sheets on my furniture and anything else that she get on. Also, I bought some spray at Wal-Mart called "Out" that will remove blood from your carpet. Hope this helps you out!!