What he's saying is that his dad turned off 'write' permissions to drive C: for everyone but himself.
As a result, he is unable to save any files (screen shots, etc) from aces high because the permissions won't allow it.
What you need to do is have your dad either re-organize his security efforts (it is unwise to lock out an entire drive like that).... or add a partition to the hard drive, creating a 'virtual' drive (D: for example) that you could use to save things to.
If he is unwilling to do this, you could always use an external hard drive, 'pen' drive... or risk getting in trouble and logging on as him and setting this up yourself.