Welcome to the community @kgalang
Thank you for sharing your programming journey with us. I find it inspiring and I am glad that you are here. Like you, I am also aiming to improve my skills and contribute to what makes this a positive community, and thus, I am glad to hear you have similar goals in mind.
Here are some few resources to help you through the on-boarding process and give you some insight on OpenMRS.
Getting started - https://wiki.openmrs.org/display/docs/Getting+Started+as+a+Developer
Using git - https://wiki.openmrs.org/display/docs/Using+Git
Sample Sprint - https://wiki.openmrs.org/display/RES/Reporting+Sprint
Sprint announcement - Sprint 9 Announcement Overview
Sprint List - https://wiki.openmrs.org/display/RES/Sprint+Schedule
Pull request tips - https://wiki.openmrs.org/display/docs/Pull+Request+Tips
Developer Guide - https://booki.flossmanuals.net/openmrs-developers-guide/support
Again, welcome to the community.