I am just out of hospital again, and somewhat behind the times, but you need to use a small amount of caution with this.

The correct answer is as follows .....

If you are ONLY using ONE pc then swdomen is correct ... However ...

If you have plans to use TWO pc's then you will need to have Multiple Battle.Net accounts.

I myself set up multiples due to a reply from Blizz when I asked them a similar question but mentioned that I sometimes use more than one computer.

Good Luck in your Endevours