Improvising really isn't as difficult as you might think. I know many of you have probably been trained in the school of "play what's on the page, dummy - and don't deviate!" but that really doesn't do anything for you when it comes time to improvise or create a solo. You'll find I maintain a fairly strong emphasis throughout my guitar lessons on how to develop your own skills improvising with the guitar.
The pentatonic scale is, in my opinion, the most important of all the guitar scales for improvising, because once you get the pattern down, you literally can't go wrong.
This lesson should give you a bit more of a feel for how to get started improvising with the pentatonic scale.
Watch the lesson on Youtube.