Install and launch Cain & Abel.

If you are using this for the first time, it will look like this:
 

Choose the one that has IP,do not choose those with 0.0.0.0...


Now,you will be prompted by something like this

Choose "Decoders" from the bar and you will see the this:
 
Choose the type of passwords that you want to search from the
computer..
 
After that,click on the "+" button

You are about to finish the job,you will see some passwords or hash...