i would second the recommendation to chck out Mississippi John Hurt.
A trio of musicians who admire his music have put together a recording
(and a tour) called Avalon blues. Chris Smither, Peter Case, and Dave
Alvin are this trio.

in order to play blues most often the "12 bar blues" pattern is used.

In order to learn which chords to play, you must first find the
foundation chord -- the one which denotes which key the song is in.
this is number one -- or l (roman numeral one) using the circle of
fifths, you determine which chords are the 4 (IV) and 5 (V) chords.

for instance in the key of A , A=I, D=4, and E=5

I, I, IV, I, V, IV, I

somehow that is only 7 bars, so now i really have the blues
cuz i can't count to twelve...i am sure there is a place where
you can get the information

blues are often in teh key of E...