How to add code to redirect when someone clicks on a menu option

Hi there, I am not live yet, but I have a line of code provided to me by the software company that will redirect potential members to have to enter their email to get pricing, when they click on that tab on my site. Would anyone be able to help me with how to set that up? 

The link is to my old site, I am trying to make my new squarespace site go live in a day or so!!

Can you share the code and how you've been asked to implement it?