Well, in the line that looks like:
<select name=""> is where the option is. Basically, use CSS to define the width you want it to be.
If you're talking about the width of it, just use a simple style tag.
<select style="width: 100px;">
If you're talking about the height of it, just add the height declaration. If you're talking about how many rows of options the user sees before it scrolls, that's not controllable by you. THat's dependant upon screen size and relative position on the screen.
~Brett