format header user logged

First of all, excuse my English (I speak Spanish and I’m not good at English), I bought this template for my website in the html format a long time ago, so much so that the link is already discontinued (Link here), before I did not need a login system, but now that I need to implement it I found that the content for logged in user is not, there is no template that shows the html of the logged user where you can see the profile picture and a button to disconnect, the problem is that I want to keep the format of the site, but I can not find the correct css for this, all this is for the part of the navbar where it appears the registration and login button, I just need to know what class are needed for it and if you can give me the html format I would appreciate it even more.