If it is the connection between the soil pipe and the toilet that is weeping then fairly easy:
Turn water off to toilet, flush it a couple of times, unbolt from floor, pull forward. Pull old connection out, cover the new one in water based lube (don't get any on the toilet lid as you'll lean on it when moving the toilet back, slide off and smash your head on the cabinet), slam it in, push toilet back on to it. Bolt toilet to floor, water on, wait and flush then have a beer. Stick a bit of card under it to test.