Other Fellows can search for you using the search fields in the Fellow Directory. However, If you want other fellows to be able to contact you, then check the "Personal contact form" box under Contact settings in My Profile.
How to contact another fellow:
Messaging: You may message other fellows directly by using the “Message” button on their profile. (Messages are no longer stored on the site for users to retrieve later. This is a more secure/private way of allowing in-site messaging.)