I am currently entering all transactions into the day books on a spreadsheet and wondered how would I record any purchases via credit card? Would I open a new spreadsheet to record all credit card transactions?
Depends upon the volume. You may wish to include everything on one tab and have a couple of columns showing how the transaction was paid (i.e. bank, cash, credit card). This way, you are simply treating the credit card as a second bank account with an overdraft.