A One Page insertion form in php/mysql - repost

I have a one page form which is already designed. The insertion part has to be done using php. There are 3-4 sub insertions associated with the main form. This work has to be done in 4 days of awarding the project. The code should be optimized and clean. This form is just a part of a bigger project. If the work is good, the entire project will be given to the freelancer... which may require 3-5 months of regular work. Just quote the cost of a single form insert, the form has around 18-20 fields, and 4 subinserts with 3 fields each. The database is in sql