If you learn all the MAJOR and MINOR CHORDS, you can usually work out some good songs or melodies from these.
A 12 bar blues is a nice chord progression, A SIMPLE WAY TO LEARN THIS TO START WITH IS TO DO IT IN THE KEY OF C.
The STRUCTURE OF IT IS LIKE THIS: -
CMAJOR, CMAJOR, C MAJOR, C MAJOR (NOTES IN CMAJOR CHORD ARE C E G)
F MAJOR, F MAJOR, C MAJOR, C MAJOR (NOTES IN F MAJOR ARE F A C)
GMAJOR, F MAJOR C MAJOR, CMAJOR (NOTES IN G MAJOR ARE G B D)
With a 12 bar blues, just get a QUAVER RHYTHM GOING IN THE RIGHT HAND, SO 1+2+3+4+, and with your left hand you could do CROTCHET RHYTHM on the 1 2 3 4 beats.
To work out MAJOR chords you do the following - Start on your ROOT NOTE, so we can say C, and you will climb up FOUR SEMITONES, to the right of your starting note, so you SHOULD now have E, and your second note in the chord, and then you climb up a further THREE SEMITONES, to get to your last note in the chord....this will be G.
For MINOR chords, you use the same formula as you do to work out MAJOR but you do it around the other way, so start on your ROOT NOTE, and climb up THREE SEMITONES, then climb up FOUR SEMITONES...
So if you were working out C MINOR, you should have C EB AND G, for your chord.
Hope this helps get you started with chords.