You can start here and see examples here. One of my simpler ones is the Waze traffic rule template: Driving Time and Distance using Waze [4.0.0.0;4.9.9.9].
At a high level you create the rule as a managed rule in the UI, which it appears you’ve already done.
Then you copy the contents of the code tab and manually add the properties same as you would for a custom widget. See [Do not install] Rule Template Parameters Experiments and Examples for a bunch of examples of different types of properties you can define and some of the options on them. You can get even more control through regular expressions and such if desired but a lot of common formats are already handled (e.g. URL, IP address, location, etc.).
Properties are applied to the rule created from the template using a find and replace. For example, if you have a property called “apitoken”, where you would put that that String in your code would become:
var bridgeApiToken = "{{apitoken}}";
Create a new posting in the marketplace category and follow the template. Test that it can be installed and configured and let a moderator know (I can do it) when it’s ready to publish as we’ll add the published tag. Then it will show up for all users in the add-on store.