To be able to play the basic progression for nearly any blues song, you will need to learn 5 basic open chords, as well as B7 and F.
Here are what the chords look like:
Play the F chord to fret the 6th string with your thumb, and the top two strings with your index finger. It should look like this:
If you are not comfortable with these chord positions, it is is essential you practice them before moving on. Practice strumming them starting with an A chord and moving through a G chord before starting again.
Once you are able to finger the basic chords, we will explore chord progressions.