How to resolve the "Missing Collateral" error notification
You are in luck as this is a very easy error to fix! Open up your Nami wallet and click on your profile picture. From here you will see a dropdown with a button labeled "Collateral". Click on this and then complete the collateral setting transaction (this requires ADA). The 5 ADA that is used for collateral will stay in your wallet, it is just set aside to ensure safe interactions with the Cardano blockchain.