Well most computers have of course a hard drive. But also, the cpu instructions can access some special memory banks, the RAM memory and the registers. RAM is the temporary memory storage used by the cpu, and registers are even more temporary banks for storing data. The cpu can address the registers and through direct and indirect addressing get at the RAM and hard drive.
The best way to get a good picture of this is to do a google image search for something like "diagram of a cpu" and check those out.
The best way to get a good picture of this is to do a google image search for something like "diagram of a cpu" and check those out.