Keys and stuff

OK I am somewhat new to a guitar no lesson but im picking it up very well i want to know 2 things ok say i am playin a C-F-Am-G Progression in the rythym i would be in the key of C correct well how would i make solo over that would I use the C major scale and since the rythym guitar doesnt stay on the same chord obviously or it would be lame would i change scales with the chord or stay in C major and the second is how do i develop a solo out of a scale when i try i find myself going up n down the scale and its lame i just need some help over here please thankz

You can stay in C major because all the chords are made up with tones that come from the C major scale. C is CEG, Am is ACD, F is FAC, G is GBD. To make your solo sound good, you ought to play the notes of the C scale, but you can also try to 'target' the tones that are in the chord in the background. Also, it's rather difficult to play something musical when practicing a scale. Master the scale, then try to sing the thing aloud. play it on the guitar. After a while, you'll be able to play it WHILE you are singing.

Try learning to play melodies within the major scale ( tv themes, nursery rhymes, classical excerpts, etc) This will teach you how to skip around in the scale to make your phrases sound more musical and less like a scale.

Try the C Dorian scale, might work nice, especially if you added one more minor chord in there.