Hmmm...well with respect to playing in different keys, within the same song you can play each chord's respective scale (or scale that compliments) as that chord comes up in the changes...basically following the root:
C major chord = C major scale
F minor chord = F minor scale

Or if you know what key the song is in (the "home" chord), you can usually stick within that respective scale throughout, but accenting different notes of that scale to compliment the changes.

Of course this is not everything there is to soloing, but is a general way to get the feel of it. Obviously I think you could learn a lot from the lessons here, but I'd say to get you started right away, learn the major & minor pentatonic box patterns. These patterns stay the same but move up and down depending on your root. This is prolly the most common scale in blues/rock.

click here for basic scale guide