1. You find tremulous.x86
2. you open a shell/console/command line, change into the directory where you have put the tremulous.x86
3. you type the following: sudo chmod u+x ./tremulous.x86
sudo = running the following command as super user / root (it will ask for your root password)
chmod = changing permissions on a file
u+x = give the group u (which is the "user" group) the permission to execute (x = execute) tremulous.x86
It is really easy - but you NEED to read about linux and how it is working. Really.
If your going to explain what it all does, at least do it right.
sudo asks for your password, not the root one, and only works if configured. su -c does what you said.
and u+x allows the user to execute it. The user and the group are very different, no such thing as the "user group"
