I have a female great dane that is just nine months old. She is my first female dog of any kind, and just went into heat for the first time starting yesterday. I was wondering how long it lasts and how often it happens. I bought her a doggie diaper and absorbent pads which she willingly wears in the house, and whenever I let her out to go potty, I take it off until she comes back in. Is this right too? She only is outside to either be exercised or go potty. Thanks.:)

Yes what you are doing is right,

The heat cycles of the female (*****) are caused and controlled by hormones that are produced and released by the ovaries and other glandular structures within the body. The ovaries are paired structures that become increasingly active when the animal passes through puberty, at the first heat cycle. This ranges from between five and eighteen months of age depending on the individual and the size of the animal. In the toy and small breeds, heat cycles occur as early as five months of age, while in the giant breeds, this may not occur until the animal is fourteen to eighteen months old. Typically, these cycles will occur every six to nine months throughout the life of the animal. In the very young and very old, there may be 'silent heats' with no outward signs that are detectable by the owner or sometimes even other dogs. Dogs do not undergo any form of menopause. There have been rare cases of heat cycles resulting in pregnancies at fifteen years of age.
The heat or estrus cycle of the female is divided into four different stages. There is great variation in the length of these cycles among individuals of the same breeds and among various different breeds. Additionally, the same animal may have significant variations over the course of a lifetime. It is therefore impossible to talk about the cycling of *****es using exact dates or times.
I took this from the below listed site, please go to it so you can finish the article (O:

http://www.peteducation.com/article....&articleid=920

Now is the time to spay her, save her all that trouble and then no longer any need for doggie diapers.

Thanks for your input. I am getting a little worried about her though. She seems that when she urinates, she leaks urine right after she gets done going. She seems to lick herself quite a bit too. I haven't noticed much bleeding over the last 24hours, but she seems to drip a little after urinating. Is there something else going on possibly? Or am I just being paranoid.. She seems to be swollen down there too. Any advice would be much appreciated. Thanks.

Sounds like she has a urine infection, make a vet appointment.

I took her to the vet, and she checked out fine. Thanks for the advice. If anything better to be safe than sorry, and it gave me peace if mind.:)