I want to play upright bass?

So I've never played the upright bass before. I'd really like to
switch to it for high school this year and I played viola for two
years, but I didn't like it at all. I'm a beginner and have only
touched a bass once before, so I really need some help on choosing the
right bass for me and what I need to know.

I'm about 5'5 1/2 and I need to know all of the basic qualities for a
bass.
Thanks