So I married Camilla but I can't get her to follow me. I thought spouces can follow you. One thing I know for sure though that Iif I marry followers like Lydia, she can be my wife and follower. So does tha mean certain wives can't follow you or am I missing something?

Also, while looking at http://www.uesp.net/wiki/Skyrim:Followers, what do they mean by joining the blades?

Certain people that you marry can't be followers, Ysolda in Whiterun doesn't follow as well.

They have to be someone who would follow you before the marriage to continue to do so afterwards.

I am yet to play it my self, but I know that later in the main quest or after it, one can make his companions Blades members.