Once your assets are ready, you'll have to deploy the contract that will govern your collection.
To deploy your smart contract you'll have to do the following
1. Pay the fixed amount of our service through MetaMask (see the price here).
2. Pay the gas associated with the deployment of your Smart Contract
You are paying this amount to the network to process the transaction.
It usually consumes ~ 3,000,000 units of gas to deploy your smart contract.
If you multiply this value with the GWEI current value, you can estimate the gas price to deploy your NFT smart contract.
After you deploy your smart contract and the transaction is approved by the network, you'll have a link to your contract and your Contract Address in your collection.