Honestly, if you're asking this question I think the task may be a little out of your scope...
Most sites are hosted on servers shoved in cabnets, in air conditioned rooms in large data centers; every part of maintenance is done remotely via FTP, SSH, SCP, etc.
I'd recommend that if you don't have a grasp of the concepts of this that you have him hire out to someone who does; you can easily nerf their install and bring the forum completely offline bu just overwriting one file you're not supposed to...
