Hey,
Firstly, we're working with Java here, not javascript! They're entirely different
Your script looks good so far, well done. As for banking, take it one step at a time. First, make the script walk to the ferry people. Initially you can use the webwalker while you sort out the logic of your script, but after that I would strongly recommend using pathwalking as you know both your source and destination. You can learn more about the functionality of these from the OSBot API
After you've got walking done, you need to interact with the ferry dude. I'm not sure how this works - maybe there are dialogues which you have to navigate, in which case you will need the dialogue API. You might not have to deal with dialogues at all however, this depends on the interaction process. Interact with the ferry dude much like you do with the fishing spot!
I've left my reply quite open ended as the best way to learn is through trying. You can perhaps ask more detailed questions here if you need more help, or alternatively ask people directly in the OSBot chatbox or the OSBot discord.
Good luck!
Apa