The deposit is about 2 months house rental. Please see the last page in the given contract.
The deposit must be paid before you can claim the keys to your apartment. If you pay a day before or the same day as you want to claim the keys, you must bring a receipt or a phone screen shot showing the transaction has been completed.
You can pay the deposit through «Your Page» or by using the account information which you can find on the last page of your contract. If you pay through Your Page using VISA or Mastercard, there will be a fee of 100 NOK to the card merchant.