[@Seeephira]

In order to tag people, ya gotta click the @mention button on the bottom right of a person's post, the one right next to the Quote button.

Won't work if you just type @personsname :P

if you click the button on any person's post you should get a [@username] thing, delete the username part and add the name in there right after the @

(I also actually accidentally tagged someone with my example thing, oops)