First, make sure you have configured your program questionnaire the way you want, so that it captures all of the information on goals and skills you'd like reports on, as well as information for pairing your participants.
Navigate to Programs > Registration, and head to the Invite Users tab.
Toggle on Registration. Your program is now visible to eligible users. Choose your method for inviting users:
Invite via email using user directory: This method gives you the most tools to analyze your reach and conversion on invitations, but you'll need to either add users one by one or upload/sync a report of them.
Public Registration: This method provides a public invite link that allows anyone with it to create new user accounts from scratch. You will need to double-check whether users who register are indeed eligible.
Invite via link: Both User Directory and Public methods allow you to share a link, if you want to post it somewhere or email it yourself.
You can see users signing up by clicking on the Registered Users tab, where the participant pool will show the breakdown of registered mentors and mentees.