So, now you have a magical glowing hole on your island, the next step is to decide how many bells you need to plant. Some people advocate only planting 10k bells, I plant 20k bells, and some especially brave individuals plant 30k bells. Once you've determined the number of bells you need to plant, you then will need to receive a bell bag (comprising that lots of bells) prepared in your stock.
If you do not know how to do so, open your inventory, pick the thing showing how many bells you're carrying, press, then choose how many bells that you wish to put in your pockets.