Hi PPonU4Me & let me add my welcome to the forum.
Jase and Roger both have good suggestions. You have a delicious dilemma . . . there is obviously some germ of a song in your head, it's just a matter of helping it happen.
Roger is very correct regarding the metre of the song - the rhythmic feel is a great place to focus. Nonsense syllables might be a way to loosen up your imagination. Just 'doo-bee-doo' and 'gabba-gabba-hay' along with your chords and see if you can find a pattern that suits your liking.
Melodic lines are fun to play with, but I would suggest getting a topic for your song first. Songs are best when they are about simple things - big ideas are hard to fit into a song. Don't feel like you have to change the world with your lyrics.
As you play your chords, what images are conjured up in your imagination. Freeze-frame an image and then ponder it a bit. What words or phrases can describe that image? See if you can get off on a flight of fancy about that image/idea.
I was recently playing around with a 1, 3b, 4, 1 chord set and it conjured up a sort of lurking/menacing feeling. So, I used that idea and wrote a little ditty entitled "Food Chain".
For me, it is helpful to jot down words or phrases otherwise the ideas evaporate. I also find that simple physical activities like walking, riding a bike, raking leaves, or doing chores lets my imagination roam freely.
Seemingly very simple ideas can be nurtured into a song. For me, it is easier to nurture and expand on a little idea than it is to compress or compact a big idea into a song.
OK - enough pie-in-the-sky junk . . . Here is a very practical suggestion:
Carry a piece of paper and pencil with you every day. Keep your ears and eyes open and alert for stuff that is neat/stupid/silly/gross/funny/sad/typical/odd/exciting/boring. Listen to the voices around you - bits of conversation or words or sounds.
Whip out that piece of paper and jot down something about what you have noticed. Do this a lot. You will soon have a whole bunch of ideas any one of which might resonate enough in your imagination to become a song.
Here is another idea that might jump start your creative juices:
Pick an object - any object big or small. Stare at it and think of all the words that can describe that thing - how it looks, how it smells, how it sounds or feels or where it is. Jot down all these descriptors. See what these words or ideas remind you of - think of other words that rhyme or sound like those words. Think of words that are opposite those words. Think of words that start with the same letters - - - the whole idea is just to exercise your mind and let your imagination wander.
Sorry to go on for so long - I guess my mind and imagination were just wandering!
James
"That darn Pythagorean Comma thing keeps messing me up!"
[url]http://en.wikipedia.org/wiki/Pythagorean_comma[/url]