[tz] Reading binary files

OK, I give up. I've tried looking at the source code and it's hopeless. Can someone please explain to me how to read the binary files and turn it into timezone information? All I need to do is write a function that will take a UTC date and convert it into a timezone with a name that I specify and convert it back again. (I understand there are precision issues with the last one.) The code is not commented and I can find no documents. Please, I beg you, help me.