You can create a contract for a gig from that gig. Info already on the gig, such as contact persons, fees and so on, is added to the contract. You can add or change items in the contract for that gig, or use the default contract for your band.
You can adjust the contents of your default contracts in the Contracts module. You can also publish your default contract as a public terms of service page, linked from your public artist page.
The default contracts in nGage are only a guideline to help you make good agreements. The points in them have worked for us in real life situations for many years. nGage.band is not a legal advisor and no rights can be derived from these example contracts.
Always, always have contracts you send to clients reviewed by a lawyer.