Follow this quick tutorial:
1. First, you need to connect your wallet and go to the Add contract page.
2. When adding a contract, choose the entrypoints which you want to subsidize.
3. Go to the My credits page and provide some credits to pay for your users transactions.
4. To relay transactions from your dApp to the Gas Station, you can use the /operation endpoint of the Gas Station API : https://ghostnet.gas-station-api.marigold.dev/operation.
Bonus: To make it easier to send operations to the Gas Station or use advanced patterns such as permits, Marigold maintains a small TypeScript library at this address: https://github.com/marigold-dev/gas-station-lib, with an example of dApp using the API.