It's free to post a note on your profile or someone else's profile, and free for visitors to read your notes.
To post a note on your own profile:
For desktop users, click My Classmates® in the top portion of any page. (For mobile users, click , you may have to expand to make your selection). Go to My Profile and select the Notes section. Write your message and click Post. You can post up to 50 notes on your profile within a 24-hour period. You can always edit or delete a note on your own profile after publishing it by either selecting the pencil icon or the trash icon.
To leave a note on another member's profile, click on their name from a Class List, search results page, or elsewhere on the site. From their full profile page, click Notes, then type your notes in the space provided and click Post. Your note can be up to 200 characters long. You can post 50 profile notes total on other people's profiles within a 24-hour period. Keep in mind that you cannot edit or delete your note after you submit it.
Notes you submit to someone else's profile will usually be published automatically, although the owner might have changed their settings and chosen to publish them manually. If that's the case, your note won't appear until they log in and publish it.