Grab yourself Guitar Tricks "full access" for a month for $5 or whatever. I wrote a whole bunch of tutorials on songwriting in my lesson section, basically going step by step throught the process of writing a song. There's a whole bunch of different ways of writing songs, but I came up with a standard way of doing one from scratch even when you have no ideas to work with.
Basically, when I've got writers block, I randomly pick a BPM to write the song in.
(mainly cause I've got gigs of loops on my HD at different speeds, so I just pick one to work with).
Then I do a search for say '120BPM'. I get a hit of about 200 or so loops that I import into my Cubase recording software. Then I spend some time sorting them into a song format like intro, verse, chorus, verse, chorus chorus, bridge, chorus, fade, end... (you do this by just using common sense by listending to the way the drum files are playing... some loop packages even sort them out for you.)
Then you grab your guitar and just start improvising to the drum trax.
You record several takes of different ideas, then kinda splice together the best ones.
Then you start adding the rest of the instruments..
Consider your first attempts as draft versions... just play whatever comes to mind.
When you finish the song, mumble a lead vocal over top of it using nonsense words. (meantime the song is already starting to form in your mind)
Then you go back and replace all the scratch recordings with performance level recordings... perfecting everything including replacing things with better snare samples or even using a real set. (the drumcorps snares at the end of the song were done with my fingers on a snare and recorded about a dozen times, then mixed down to stereo)
You write the lyrics based on what you were mumbling and try to come up with something that makes sense. If you get lucky you come up with something profound.
Then you set the song aside for awhile and come back to it later with fresh ears. Fix any parts that make you uncomfortable and edit down anything that doesn't make the song flow.
Last but not least, do a final vocal.
Then mix it and master it. (use something like t-Racks)
Overall, if you really want to do a decent recording figure on spending several weeks or even months working on it.
I posted a bunch of diary entries on some earlier songs I wrote if it'll help any.
* best thing to do is listen with headphones nice and loud, so you can hear what's happening stereo wise...
The whole thing was done on a Mac G3 using Cubase, and basic instruments plugged direct into the audio input. The overdrive on the guitar and feedback was done using the computer speakers.
... here's the diary notes for it...
That was like, the second song I ever recorded on multitrack so it'll give you a good idea of the hassles I went through.
Then there's this one:
Here's the log for it. This is the song from hell that took me two months of work.
If you subscribe to full access, it takes your through the whole process with diagrams, screen shots, mp3's and other stuff.
Hope that helps!