What do you mean 'play the blues'? It's a broad subject
I play blues with my band, basically just 12-bar I-IV-V progressions in a certain key. Eg, 12-bar blues in A
A A A A
D D A A
E D A E
Take the blues scale to play over that (hey, it's called a blues scale for a reason

). Alternatively, a lot of basic blues is just taking notes from the major scale (the 1, 3 and 5th degrees).
(I'm not an expert at this, so I might be wrong on a few little things).
There's a lot of information out there, and here on talkbass, if you look for it. Try searching for '12 bar blues'.