Before you do make a dispute on a charge on your credit card contact the merchant who'm you've bought the merchandise or service from and see if they'll rectify the problem.
Disputing a charge on your credit card is a hassle and also the merchant will be charged a fee for having the money returned to you from their credit card processor.
Most merchants will do their best to make things right with you the customer and should gladly refund you the money.
If you do have merchandise though you should send the merchandise back if they do refund you or you dispute a charge.
To dispute a charge on your credit card though you contact the credit card company and let them know about the problem.
When you contact the credit card company tell them you'd like to dispute a charge on the credit card and you'll need to provide information to them and prove that you didn't get the item or service or the item was damaged etc.
The dispute can take from 30 to 60 days before being decided and the money returned to you.