Need help with image upload in theme options page.

Hi,

I am coding a Theme Options page for a theme I am working on, however am running in to issues when trying to allow users to upload their own logo.

Pastebin: https://pastebin.com/VN51GkMG

At the moment, the theme options page displays with the relevant forms, including the upload box and button, however they are not functional, the upload button should allow a user to select an image, preferably through using the WP upload library.

Can anyone shed any light on what I need to do? I know that I will have to launch the media-upload.php file and have tried to do so through the button but to no avail.

Thanks for your time.