How to check the model and memory of their machine at home
To see how much RAM is installed, choose About This Mac from the Apple Menu. The Memory field specifies the amount of RAM installed in the computer.
How to backup their data
Using Time Machine
Time Machine is the built-in backup that works with your Mac and an external drive (sold separately) or Time Capsule. Connect the drive, assign it to Time Machine, and start enjoying some peace of mind. Time Machine automatically backs up your entire Mac, including system files, applications, accounts, preferences, music, photos, movies, and documents. But what makes Time Machine different from other backup applications is that it not only keeps a spare copy of every file, it remembers how your system looked on any given day—so you can revisit your Mac as it appeared in the past.
Setting up Time Machine is as easy as connecting an external drive to your Mac via Thunderbolt, FireWire or USB. You can also use a secondary internal drive if your desktop Mac has one (that is, a drive that you don’t start up from).
If you haven’t specified a Time Machine backup device yet, the first time you connect an external drive, Time Machine asks if you would like to use it as a Backup Disk.
Click “Use as Backup Disk” to confirm you want to use the drive for Time Machine backups. Time Machine preferences will then open with this drive selected as your backup.
On OS X Lion, check “Encrypt Backup Disk” if you want to encrypt the Time Machine backup external drive using FileVault 2.
That’s all you have to do for Time Machine to automatically backup your Mac. Time Machine keeps hourly backups for the past 24 hours, daily backups for the past month, and weekly backups until your backup drive is full.