When graduated and thinking hard problems by own, how to get help on hard parts?

I graduated from maths with better than average grades. But on my free time I would like to learn a book Qing Liu: Algebraic Geometry and Arithmetic Curves on my own. The problem is that it has some really difficult problems I can't do. I asked the author of the book a hint for a particular problem but he was not willing to help. Here is an example problem: http://ift.tt/1CNEq7Y

What would be the best way to learn to do difficult problems on my own or get some personal guide to help me through the hard parts? Should I hire a personal teacher or what?