How exactly do I use the linked lists to turn two characters on either 'side' of the colon into integers?

The linked list would store your records, not perform any transformations on them. So you'd extract the data, format it however you want, then store it in a linked list (or array if you'd like) for later printing.

Extract FROm the linked list, or wherever I make them to then put in the linked list?

The linked list is a storage mechanism. Wherever you're currently printing, add to the list instead. Then you have the data in memory and can print it later at your leisure.

Okay. How do I get the printed results into a linked list?