Charging for web content

Not sure where this goes, so I'm putting it here.

A realtor I know has asked me to write some content for her website--information about the area where we live to attract young couples etc. to live here. I took the job on, but I've never done anything like this before. I've found a little bit of information on how to actually write content for the web, but I can't seem to find any information on how to charge for it.

Obviously, I don't want to charge her professional rates--I'm a college student, not a professional. However, I don't want to lowball myself. So I have two questions: one, how is pricing on web content figured? Hourly? By the paragraph? By the word? Two, how much does the average content writer charge, and what would be a good adjustment to that fee for my purposes?

Jam it back in, in the dark.