Error message: "Access Denied" in MySQL

[weepstick]

When I watch tutorials on videos, theirs work but when I try it, it says 'access denied'. I installed MySQL shell, but no matter what command I type, it says 'not connected'. A foreign website instructed to run the following command '\connect root@localhost', but when I tried that, it also said 'access denied'. Thus, I found myself caught in a loop.