Though I am glad to help at any particular question, it is hard to tell you where to start without knowing first exactly what you know. What I recommend is that first you do a lot of reading about hteory, so that you know what questions to ask. Here is a good website with theory on it, that should help you a lot http://www.zentao.com/guitar/theory . As for where you should start, I advise you learn the major scale in C at least, and the patterns for it over the fretboard.