Even I got stuck at same place.
I used 'man' command to see what's the problem with 'alias' command.
According to this terminal there is no 'alias' command.
$ man alias No manual entry for alias
The lack of a man page doesn't mean the command doesn't exist.
$ aoeuhtns bash: aoeuhtns: command not found $ alias $
See the difference?
And bash might have something to say about its built-in commands:
$ help alias alias: alias [-p] [name[=value] ... ] Define or display aliases. ...