Narz,
This explaination could be lengthy and there are many pages written to help with databases. First thing to find out is, are databases included with your hosting account? If so, they probably have a guide on how to work with their system on setting it up. After that, I suggest you look at http://www.sqlcourse.com/. SQL is a standardized language (for the most part) and this page pretty much lays it out, and as I remember will be easy for a beginner.
Hope this helps,
Tom
P.S. Forgot about the part of getting it from the form. How new are you to PHP? I need to know where to start 😛