If you have been infected with this, you should disconnect your computer from the internet immedeatly in an attempt to minimize damage, though it may already be too late.
The crypto virus is spread primarily via Email, usually as fake UPS or Fedex notifications with tracking numbers. Once you click on the tracking numbers, you can download and infect your system.
Once the system is infected, the virus encrypts files on your computer. These encrypted files are locked from you, and you are given time (usually 100 or 72 hours) to pay the ransom to get your files back. The ransom is typically $100 or $300.