Adding drop down via functions.php - wordpress

Wasn't sure if this should be in the wordpress section instead.... but I am using the PaidMembershipsPro free version plugin so don't get free support.

When signing up I wanted to add a few extra fields and found the code on github to add to the functions.php for adding input fields which works fine.
https://gist.github.com/strangerstudios/1389944

However, I wasn't sure how to add a select/drop down instead of input field.
I know I would have to update other parts of the script, but just to display the drop down correctly, could someone tell me how to replace the following with a drop down with say 2 or 3 selections?

<div>
<label for="firstname">First Name</label>
<input id="firstname" name="firstname" type="text" class="input" size="30" value="<?=esc_attr($firstname)?>" />
</div>

Maybe replace with a simple drop down:
<label for="gender">Select Gender</label>
<select name="gender" id="gender">
<option value="male">male</option>
<option value="female">female</option>
</select>

Wasn't sure where or how to add this from the first example:
value="<?=esc_attr($firstname)?>"

thanks!!