Andor's Trail

How do I apply my codes to my AT on mobile?

Sorry, but I don't understand your question. What codes?

I mean, can I add some codes that I've written directly to my Andor's Trail on my phone? Or I must use a computer to do so?

Based on other posts as well as this one, I assume you mean modify AT by adding or changing code (Java, or JSON content). You can't do that from a phone. You would need to pull the current sources from github, make your changes, recompile, and move the new version to your phone. If you don't want to recompile your own version you would have to push your changes back to github, and then issue a pull request. They will (eventually) be reviewed and either accepted or not. One other option is to post what you have done here (in the Ideas in Motion section).

Actually, you can do so on your phone or tablet, by using AIDE or an equivalent app.