There are several options for inviting people to your Group Page.
When creating a new Group Page (from your Dashboard tab), proceed to Step 4, Sharing. You may then choose from copying invitation text to paste in your email or eNewsletter, text for sharing on Facebook & Twitter, and an HTML button you can add to your website or blog. Choose as many options as you like.
If your Group Page is live already, login to Signup.com and open your Group Page in the Dashboard tab, find your Group Page, select Manage and click on Step 4 - Sharing (as shown above).
NOTE: To send invitations to participants across multiple SignUps or those associated with the SignUps posted on your Group Page(s), please choose Advanced Messaging from the My Tools Menu.
Learn more about Setting Up Your Group Page here.