//I am getting this message, whenever i try to update or upgrade my m/c

aatif@haider:~$ sudo apt-get install update
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Couldn't find package update
aatif@haider:~$ sudo apt-get install upgrade
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Couldn't find package upgrade
aatif@haider:~$