You need to create a file named ".profile" in your home dir (/home/user).

In this file you can declare any shorthand you like for long commands, using the "alias" syntax, like this :

alias cls=clear
alias l='ls -l'
alias ll='ls -al'
alias docs='cd MyDocs/.documents'
etc. ...

Then you make that file executable using :
chmod +x .profile

From then on, when you run xterm, the .profile will be executed for you and all your aliases will be available.