Okay, so I have no problem writing guitar riffs. It's making full songs that seems to keep getting me. I'll make a main riff that I want the song focused around, but then it just goes blah after that. Here's an example of a basic riff I've written:

e|-----------------------------------
b|-----------------------------------
g|-----------------------------------
d|-----------7-7-----3-2---5--------
a|------0-3--5-5---------3-3--------
d|-0-3-------------------------------

and then there's a "build-up" version

e|--------------------------------------------------
b|--------------------------------------------------
g|--------------------------------------------------
d|------------7-7---3-2---5-3/7--------------------
a|------0-3---5-5-------3---------8-7---8-7---8-7--
d|-0-3--------------------------8-----7------8----9-

All I end up doing after playing these riffs is falling back into strumming some power chords... any help on building songs would be nice... like what could I do after this???