SCRIPT Problem

Ok im not shure how to do this so here it goes, Ok, i am making a form for a client that has some combo boxes so they can click the down button and select stuff from it. Well at the end of this form i need to make what they selected in those combo boxes e-mail to the guy. I use php, i did this with his contact form but it was with input text so i could just simply give it a variable name in the properties of the input text and load it into the php script like

PHP:
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E-mail: $email

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and the $email is the variable name. But with the component combo box there is no area to enter a variable name in the properties of it. I tried just giving it an instance name and doing this in php to load what they selected
PHP:
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Selection: $combobox

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but it wont work with the instance name. So how do i make what they selected go into the php script and e-mail to the guy?