Tell us more things:
1. which database is the one you are working with.
2. do you have a table and an apropiate field to store the value?
3. what have you tried so far?
4. which are the problems you've found?
...
There are tons of tutorials on how to work with databases using php in the internet...
As you are speaking of a radiobutton, I would use any kind of numeric variable to store its value there...
Please, give us more details and we will try to help you.
PS: You should use a sql query to store the value... could you show us the complete code?
PS2: Take a look here:
http://www.php.net/manual/en/ref.mysql.php... it should help...