Well, for a start theres a huge guide on this in the game under the tutorial menu. You were also taught this in the first disc right after starting (first outside garden before ifrit's cave Quistis teaches you about junctioning GFs and magic. then right after getting Ifrit Quistis teaches about Elemental junctions (and status junctions too if I remember right) I reccomend these again as they're visual. As for your levels...I personally think your levels are too low. I'd have been atleast level 50 around this point in time. As for refining the magic, first you need the corresponding items and abilities to make it. My advice go level up from an earlier save and watch the tutorials in the menu.