Using steemit after a long time

Lots of things have changed here, i stopped using steemit like 3 years back and logging in was a mission. As there are so many keys and I had no idea which one to use, finally I had one that was accepted but thn It asked for another key which is supposed to be for posting and somehow I had that also.

After I login it created a Tron account for me which I have no idea what it is used for as of now. If there is a video that could explain about the changes would be helpful for me.