Inserting into mysql with a multiselect box WITH PHP

[alvdy]

Hello There guys.
Ages since ive posted been busy with school etc.
I am doing a computing course that requires HTML and PHP and MYSQL database. HERE

I have an order form that has a multiselect box on it.
http://comp.waimate-high.school.nz/apoc/Admin Page.htm

As you can see you can select just one or both of the values in the size box.
How do i upload these values to the Database if just one is selected or if both are selected??? How do i need to set the database to recieve multiple values?


The HTML for the form is HERE
The form posts to a php file insert.php available HERE

Thanks
Allan