12 bar blues/chord theory

whats a 12 bar blues progression? what is some chord theory here. i wana be able to connect chords with scales, i kinda know how but not like too well, like i know what makes the chords nd stuff but i dont know the shape, like i know tht maj is 1 3 5 min 1 flat3 5 dim 1 b3 b5 and so on, but what is the shapes of some chords like dim7 dom7 whats the diff between some of those chords and how do they fit into a scale and key? thnx.

Check out my first topic! :D

and then my next question of whats the general shape of them