Hi,
Getting the value from a dropdown passed to a PHP script is the same as getting the value from a text input passed to the PHP script. Make sure that in the HTML in the opening select tag you declare a name (ex: <select name="color">). Then give each option a value (ex: <option value="blue">Blue</option>). What PHP will see as the value of $_POST['color'] will be the value of the option selected. If you have a group of radio buttons, give each the same name. Assign them different values.
Example:
Code:
<input type="radio" name="sign_up" value="yes_signup" />Yes<br />
<input type="radio" name="sign_up" value="no_signup" />No<br />
In your PHP code, to get the radio button the person selected, use $_POST['sign_up']. If the user selected the first radio, the value of $_POST['sign_up'] would be "yes_signup". You can read more about PHP forms at http://www.w3schools.com/php/php_forms.asp.