Obi-1,
MSPOS cannot use PCCharge at this time, you must use the built-in with Vital.
To set it up, POS Manager | Tools | Options | Tender tab | check Use this payment processing | Setup button | fill in the info from your bank/processor
The yellow boxes are needed for credit cards, the white ones are also needed for debit cards.
Make sure you have _all_ of the info before filling anything in, find a form attached for the info required from the bank/processor, have them fill it out and send it back to you.
THEN,
after making your changes, you need to change the tenders to recognize the changes made. For each credit card tender, check the box for Verify using payment processing service on the Advanced button. POS Manager | Store | Tender types | select your credit card | Advanced button