How do I enable the Pop-Up button for this?

Hi,

I am looking for a Pop up overlay with Contact Form.

Say for example in my site I want the menu "Join Us"
On tap of "Join us" the overlay(popup) with the contact form/login form should appear.
Something like this if you tap on "Contribute" there is a popup with a overlay "Volunteer" "Shop" "Donate"
I need to replace these with Login form or contact form.

Could you please help me how do I achieve this?

I have used the PopUp Pro plugin but not sure how can I achieve this.

Btw,
happy new year.