Need to autofill a web form with a database (csv) file.

I need to be able to take data from a csv file and auto fill the data into a checkout page of a website. I know firefox has a plugin for an autofill feature but I can't seem to figure it out. The data will have the same 7 fields (name, address 1, address 2, city, state, country, zip code), but the information in those fields will change daily. Please pmb me if you are not clear on what I am needing.