Pls help ur homegirl out

Asking this for the 3rd time now i am gonna cry pls

can someone pls tell me how do i add my own tags on smthng i read? Like when i type smthng on the "add tag" space nothing happens i can only either add the recent tags or the tags that already exists in that story

Ik i am supposed to press "enter" which is nowhere to exist in my phone bc ion use my PC to read manga so i am lost I've tried doing everything but nothing works maybe i am just dumb asf I'll really appreciate it if someone can help me with this if possible pls explain me through screenshots so that my dumb ass can finna get it thankyou in advance <33