Hello,
By “gateway” I assume you mean the WooCommerce Cryptocurrency Payment Gateway extension.
For your coin to appear as an option on checkout, the plugin must know the exchange rate between your coin and the base currency of your shop, AND the user must have enough funds to pay for the value of the cart.
To make the exchange rate known, you can do either of two things:
1. You can either set up a fixed exchange rate that you specify yourself, or pull it from an external API using PHP curl. Please have a look here: https://gist.github.com/alex-georgiou/492196184f206002c864225180ca8fbb
You can edit this file, then add it into your plugins directory and activate it as a new plugin. It will act as an “Exchange rates provider” for your coin. Whatever exchange rate you set will be used to price your products/services.
2. If you have also set up a market for your coin using the Exchange extension, there is another way: Simply go to the market settings and enable the “Use exchange rate” checkbox.
Please let me know if you have any questions about this. You an also have a look at the troubleshooting section of the payment gateway homepage for more info.
with regards