Jolie-Chan

this site isn`t meant for social netwoking like this originally, so it`s kinda complicated.
you can only get to a certain users profile, if you click on their username (unless you bookmarked their profile already).

so if you can contact your friend outside from mangago, you can ask Hoshie to write something on your meassage board and you write something on theirs.
if you can`t contact Hoshie otherwise, do you know a manga your friend really likes?
then you could go to the manga page and take a look at the bottom to the right under "They read this manga" and search there for the username or maybe your friend left a comment?
or maybe Hoshie has made a list with a certain manga you remember...

once you found your friend, maybe you`d like to click on "follow this list" (if your friend has a list) because then you can find this list on your profile too and can get to your friends profile anytime, though it would be easier to keep in contact if you write something on their message board and your friend writes something on yours

wish u good luck!

Thanks Sakuracry for this Answer ;o)