First, edit your ~/.bashrc
and make sure that it contains the following three lines (if not add them editing the file)
if [ -f ~/.bash_aliases ]; then
After this all you have to do is edit your ~/.bash_aliases file and add your own aliases.
alias dld='cd ~/downloads'
alias x11='nano /etc/X11/XF86Config-4′
alias pak='cd /var/cache/apt/archives'
Save and exit the file.
In the above examples, "dld", "x11" and "pak" commands will execute the exact command from the right side of the equal sign.