How do I replace the fuel lines?

I have a Weedeater 25cc hedge trimmer and the fuel lines broke due to "old age". My son pulled everything out without really paying attention to where things got put back. I've got the lines into the tank and now I"m ready to hook 'em up to the carb but can't really figure out where/what order the two lines go. Any suggestions? Also, any suggestions on how to get the lines onto the nipples?