The preferred way to deploy a smart contract on the Watr network is to use WASM smart contracts that are typically compiled from ink. Ink is a set of rust macros that allow for the definition of WASM contracts.
The first step is to set up your local development environment. You can follow the instructions on the Substrate website here. This will create a Substrate sample contract, set up a local Substrate node, deploy your sample contract to the local node, and provide a UI to interact with your sample contract.