This is a picture of a hard disk which is basically remembers all the files stored in the disk it is basically a storage filer
RAM is an acronym for Random Access Memory.The use for the RAM is to store things much like the hard disk but stores in a random form
The cooling fan is basically used to make sure the system doesn't overheat
The motherboard is basically what holds everything together, it holds things such as the CPU(Central Processing Unit) and other things of that nature