Planning on visiting July31-Aug 2 - Dont have reservations!

[rowzz2]

I plan on tent camping from July 31 - Aug 2. This will be my first time to Yosemite so I'm not sure how this works exactly. I've read online about Camp 4 and that they dont take reservations but are on a first come, first served basis. Also read the ranger arrives at 8:30 am to start taking reservations, so I plan on arriving at 5am or so to get in line at this rangers station so that I can hopefully get a place to put my tent. But now I'm worried about showing up at 5am and there are no spots to be given out. Can someone please tell me how this works?
Any other suggestions for campsites near this area where I don't need to have reservations?
I'm also willing to buy someones site if anyone is interested.

Any info will help. Thanks!