Discourse view file update does not reflect in browser

for category i want to add a small image before each category name for ex

  • image/icon category-name topic-count
    description

for login i want to be validated the user from my server before login to discourse server
ex: if user enters email and password i want to send it to server if user existing in my server then continue discourse logins otherwise display message as user not existing

is this details give an idea what i want to do

i have also attached a small diagram what i want