I've got a github page(lc87624.github.com), and that i want my domain names("www.gemoji.me" and "blog.gemoji.me") connect to this site. I consider adding two CNAME record pointing to "lc87624.github.com", however when I visit my domain names, it shows a error page of github saying "Page doesn't exist! ". Someone might help me?

PS: My github page is really a blog utilizing a framework named "octopress", and that i have added a CNAME file towards the source branch.

I checked your repo and located that you simply haven't own a CNAME file inside your master branch, that was accustomed to show your website. You may didn't remember to generate the website after added the CNAME file for your source.
You are able to take a look at MINE. :)