What can I do to convince my advisor of my ideas?
First step is to have good ideas. :)

But wait, you are starting your phd, by definition, you wouldn't know what a good idea is, you do not have the experience (usually, let's leave the genius outliers aside for now). 

When I have a crazy idea, I develop it a bit, to see where it leads. If leads somewhere interesting, I prepare a nice, informative presentation, and schedule a meeting with the boss. Sometimes I get shot down, sometimes the idea is accepted, but "preparing the field" is important. You need to present your ideas properly, in a well prepared manner, to increase the chances he would understand it. And clearly presenting ideas is the bread and butter of research. 

With that said, have you tried an honest conversation with him on this aspect? Nothing wrong with an student telling me he is lost and he needs a concrete direction. Even better if that direction has specific, detailed objectives, including some easily attainable ones to keep the morale high.

Be honest, be polite, be patient, and be clear.