If you are that new, go buy a gun annual ("wish book"). They have them at magazine stores and the Wally-World. Start your research there. It will put pics and prices at your fingertips. Many gun stores discount on most items. Some brands sell at a premium above MSRP.
As you narrow your choices, go to the web sites of the models that interest you.
Any caliber of .38 special or above is adequate for personal defense against two legged predators.
9mm seems to be the most popular and is the cheapest of the centerfire calibers to practice with.
Take the N.R.A.Safety course. It will familiarize you with manual of arms and saftey issues.
These are just to start.
Read through the forums to gain other peoples opinions and experiences. These same questions are covered regularly.
Read this article. It was written by someone a lot more wise than me.
P.S. Wecome aboard.