In short. On GitHub on your fork you can make a pull request of your branch. This pull request will then go against the openHAB-addons repo and next your pull request will be reviewed and when all is ok it will be merged and become part of distribution.
What Bruce says. The pull request should be done against the main branch. Which means it should be for openHAB 3 and (which will run on Java 11).
With the start of openHAB 3 development on the openhab-addons repo the basis was ‘reset’. This means an old branch is out-of-sync with the new repo. It is probably the easiest to start with a fresh branch created from the new main. Run the skeleton script to create the basis for your binding (Which modifies all other necessary files) and then copy your binding code in the newly created code and follow Guide: Binding development changes for openHAB 3 (from 2.5.x) to make it compatible with openHAB 3.
To get through the review process quicker. Make sure you have all required files and additional files modified. Make sure you follow general Java coding standards. Make sure the readme is complete. Make sure it compiles (by running maven). Fix relevant compile warnings. Run mvn spotless:apply. Already merged bindings are a good starting point to see what other files need to be modified and make sure your commits are properly signed off.