Changing Custom Single Posts Templates & Sidebars

I need to make a custom single post template and I’ve been trying for over 12hours and can’t make it work. I have the plugins but I really need some codes.
Basically I’m making 2 blog sections for 2 different authors on the site and wanted to make it a little custom for each. I’ve done this before on a different theme but I can’t seem to do it now. I really need to do different sidebars but can’t figure out the codes.

Any chance someone could help me? I’m going crazy.