1st Install, but Username&Password Incorrect?

MichaelTheGamer

Hey there,
My name is Michael and I just became an LF member. I tried to install Mint 19 Tara with MATE DE, and even after several attempts and a few with CMD lines like the no display driver one, for example, it still boots to a desktop (normal as far as I can tell but a Linux Noob even though can do some C prog'ing lol and knew a little UNIX...I know, seems impossible, but just unsure of what, in Linux, compares to what I know). Desktop has word mint in up-L corner, all else is Win- like and the one barrier: login window. Tried mint and Enter for user/pw...plus several others. Madness has set in. But still harmless. Anyway, does anyone know sol'n? Please help!
Thank you,
Michael