Hello @Cemcat! First welcome to the community and very amazing to hear that you want to contribute to it. Sadly did you choose probably the wrong node for that (more about that below)
But to answer your question first. You can add the node like described here to the n8n repository:
and then create a pull request as described here:
https://help.github.com/en/github/collaborating-with-issues-and-pull-requests/creating-a-pull-request
Now back to why it is probably the wrong node to contriute. The reason is that I would probably not merge/add it.
There is a discussion about such a node here and what makes it so complicated to create to work at scale:
The issue is that if we add the simple version of such a node, people will not be aware of the implications. Meaning if a node exists and they have the need to wait a week between two nodes they would use it for that and that is very dangerous. The reason is that workflows would keep on running and so be active for the whole time and eat resources until the server crashes. And even worst, all the data of all that active workflows would be lost as it never has been saved (as it does only get saved after the workflow finishes execution).
So when I add such a node I want to be sure that it is “secure” to use for all people by temporarily stopping the workflow, saving the data and then spinning it up again. Hope that makes sense.