I have Acid Pro and I create music through my computer. First I come up with a good chord progression. Having hundreds of instrument loops at my disposal can really encourages my creative juices to get flowing. Once I get a good beat going, I work out a chord progression. These progressions are usually 2 to three chords with a turn-around. Once I get that going, I'll work out a lead solo using pentatonic scales or boxed patterns of the scale. I use the B B KING approach a first (motifs, call and response tricks). Kinda like scat'n over the progression. I lay down 3 or 4 guitar tracks this way. Then... I'll go back and play each track seperately and pick out the best and intellegent playing. The guitar has to say something. I'll then go on to the other tracks and edit them seperatly. Lastly, I'll clip and paste all the best parts together and create a lead guitar composition. Now you can go back and put in some fancy riffin' in the dead spots. Scales, Arppegios, Cool Licks and Runs etc. This way will help you lay down some basic ideas to build upon.

Hope this helps...