To change directories you need to supply two things at a minimum, the command and the path to change to.
The command is 'cd'. If you log into a konsole, as a user, you are usually in your home directory. All paths in linux are referenced from the root, '/' So, your home directory is represented as /home/yourusername.
You can check at any time where you are by typing 'pwd' and pressing enter. 'pwd' is the command present working directory.
So if you oepn a console, it will open as user in the home directory. Here is a sample of what this looks like on my machine.
[cliff@sluggy cliff]$ pwd
[cliff@sluggy cliff]$ cd tmp
[cliff@sluggy tmp]$ pwd
I did a pwd right after opening a konsole. It tells me form the root '/' next is home and next is cliff.
To change from my home directroy to the tmp directory, I entered the command 'cd' and the relative path I wanted to go to, in this case 'tmp'. I did another 'pwd' and now from teh root directory I'm in /home/cliff/tmp.
If I had done a cd /tmp this path is diferent than cd tmp. Putting the / (slash) in says " starting at root, change to tmp. That will only work if infact I have a tmp directroy off the root.
Hope this helps.