php mysql data entry script

Hello Guys, I am using regkeeper dot com software for the data entry of my orders received. Regkeeper is a window based software. I want to create a simple dataentry form on the web through which I can enter new orders online. I assume there are 3 tables the database is using, orders, customers, products so the dataentry has to be done joining those tables maintaing the relationship of the tables. For example on a new sales order. 1. The order id should be generated ( incremental ) 2. New customer should be generated 3. Products / service should be from the products name / product Id table etc. So basically I need a simple php script which can enter new orders online instead of the window based software. I am not too much keen on layouts, a simple professional layout with the require functionality is what i am looking for. I dont need an admin area etc. I just need a simple php script through which I can post new orders in the mysql database the same way as I do with the window based regkeeper software. I dont have large budget for this so please keep it small. Thanks a lot for your time.