Go to Transactions > Credit Card Import > Import Credit Card (menu path may differ depending on role).
There are two options:
Use the left option (Single) to import one file for one credit card account.
Select the credit card account.
Select the file from your computer. Click Submit.
After submit you will be redirected to the credit card statement in create mode.
Use the right option (Multiple) to import one file for multiple accounts. (See Setup Multi-Account Statement Import on how to setup this feature.) After submit the file will be split into one or more Statements to Process. The result will be listed and the user can click through to one of the statements.
They can also be found Transactions > Credit Card Import > Credit Card Statements to Process.