Need Help. Several Questions On New Website?

I just created a new website recently www.mathtipsandtricks.com and i'm having a few problems. I have 50 members but its only showing the facebook connect members. I am using wp fb connect plugin and buddypress and I don't know how to sync my members together. I'm also having problems with bad coding, dead links, oversized files and many other issues whenever I do a diagnostics test for my site but I have no idea how to fix any of these. What is the easiest way to do so? My final question is how do I create backlinks and get a higher google page ranking. Thanks.