Go down the shop and buy some?
Failing that if you can locate a solitary scrap of toilet paper, fold it into quarters and tear off the corner making a hole in the middle on the paper. Stick your finger through it, wipe, remove dook with the paper by pulling paper off your finger. Remove dook from under finger nail with the small corner you took off.
That was the first thing I learnt on exercise in Army Cadets. I ate garibaldi biscuits all weekend to get constipation. Following Wednesday I fired out a lord. Good times.