1) create a form where people can enter their information.
2) create a script that can read the information from the form.
3) create the SQL statement to insert the data into the form.
4) change the script so that it first checks to see if the information that the user entered already exists.
(so people can't enter their data twice)
5) Add a logon feature, so people can choose to logon or enter their data for the first time.
6) Add sessions or cookies so you can remember who logged on, and wether they are stil logged on.
7) make a new form that lets people change their data (that includes pre-filling out the form with the current data)
8) Create a script/sql statement that will update the changed data in the database.
9) treat yourself to a cup of coffee.