Looking to get into Ranked

I'd like to get into Ranked play, problem is I'm pretty much self taught. I don't really have friends I play with. I've done some looking on the internet at certain builds but I would like to understand the point behind such choices so I can better adapt them to my own play style. I'm most comfortable with traditional supports, Soraka Janna, Sona and Nami. If anyone is willing to help coach me, thanks in advance. The most help I need is with Runes and warding. I do have Skype.