There's a "add comment" button in each users profile..
Where does the comment show?
Cheers
By default SMF doesn't have profile comments so it must be a mod, check what mods do you have installed, most of the profile comments mods actually show the comments on the very same profile page.
I dont have a mod which does that..
Here's my mods.
(https://www.simplemachines.org/community/proxy.php?request=http%3A%2F%2Fs12.postimage.org%2Fnph9ha0p7%2FUntitled.png&hash=c1385d48dbd06b1e132140456f1b9745e6b611a6)
1- As Suki already said, SMF does not have "profile comments" as a feature, so you MUST have added a mod
2- there was no list....
Theres also the possibility of you using one of those services/sites that allows you to have a pre-built SMF forum ready to use on their own servers, in that case they pretty much control what they offer to you and you are pretty limited as to what you can actually do in terms of customization, so it is possible to have some kind of profile comments without you installing a mod.
But in that case you must talk to the site owners/runners of such site/service as SMF as a forum script has no interference on their business.
Of course that is just a hunch, hard to actually give you some kind of correct answer or the answer you are looking for without much more details from you.
http://s12.postimage.org/nph9ha0p7/Untitled.png
^ your image didn't display properly.
And, Ultimate Profile does profile comments. So that's your MOD.
You either have to manually make UP's show by default in the admin panel. Admin > Modification Settings > UP
Or members need to activate it themselves under Profile > Forum Profile > UP
Comments will show at the bottom of UP's
It isnt even enabled.. ill uninstall it.
Cheers