You need to get the new tremulous.x86 file which is on your desktop, to where the same, older file is located and replace it.
In your case if the old/original tremulous.x86 is in /usr/lib/tremulous then you need to move the file on your desktop (if indeed that's where it is) to that location and replace the existing file under the same name.
You wont be able to do this as a regular user (under normal circumstances) so you need to do it as root.
One way to accomplish this - as already stated - is via the command line.
sudo cp /home/YOURUSERNAME/Desktop/tremulous.x86 /usr/lib/tremulous
I tried that but it said in the terminal :
cp: cannot stat `PATH_OF_ORIGINAL_TREMULOUS': No such file or directory
any suggestions on that.
The code you were given was:
sudo cp PATH_OF_ORIGINAL_TREMULOUS /usr/lib/tremulous
He must have meant PATH_OF_NEW_TREMULOUS but still...
It should be clear enough that simply typing PATH_OF_NEW_TREMULOUS is not what was meant. Things explained like
that require you to substitute what would be appropriate on your machine.
Therefore, where ive said "sudo cp /home/YOURUSERNAME etc etc" it will require you to enter the correct detail (your username) and replace the uppercase characters.
For clarity's sake then:
sudo cp /PATH-TO-NEW-TREMULOUS/tremulous.x86 /usr/lib/tremulous
Becomes the following if the file resides on your desktop:
sudo cp /home/USERNAME/Desktop/tremulous.x86 /usr/lib/tremulous
Failing that. Fire up you file manager as root and just copy/paste the thing across.
Has anyone seen where my life went?