Gallery linked to External Site

Hello All, 

I am fairly new to SquareSpace and I like what I've been able accomplish so far.   I would like to be able to link (or embed) my gallery page to an external site that offers more flexibility in selling work product than this platform.  In practical use, a visitor or client would come to my site, click Gallery from the menu or header and would be transported to the external site. They would complete their session there and return to my SquareSpace site.  

If this cannot be accomplished directly, what's the next best way to simulate this? 

Thanks, 

Marc Spicer/ImageWerkx

Add a button or text link to the external site underneath the gallery block or on the gallery section. 

Thank you.  I was hoping for a more direct method like placing the URL in the URL Slug.  

Marc