Chosing a dog for obidience and agility...

[pick]

Hi I have been 2 months looking books and internet about dogs for agility and obidience. Since from 60 days I have choosed a portuguese pondengo, but since I have been visiting school dogs and talking with (creators/breeders??
I'm sorry, I am portuguese and I just have a little dificultie to translate: how I say somoene who always have dogs breeding with race for sale??)

Well the point is: they told me that all what I have been searched is wrong or not correctly at all. I don't know what to do, woh we choose a good dog for agility/obidience?

By the way: I live in apartment, sow it's good if he gets well in a place with any garden or like that (but with a lot of walks and exercises_the best I could get to himXD)

Can any1 else hope me choosing? I'm confused... =(