There are different kinds of developer, e.g. Web, Apps, ERP, System, etc. Different applications/platform may use different programming languages and have specific domain knowledge. I recommend you to take the Computer Science course in the college to give an overview before you decide which sector you would like to develop your career.
Having said that, you can start doing programming first. Below are my suggestions:
1. Identify an easy programming language, e.g. Python, Scratch, etc.
2. Learn the language structure and syntax. There are plenty resources online.
3. Start doing some simple programming and can do some small projects, e.g. control a toy car, robots, etc. Practice makes perfect!
4 After you have familiar one programming, you can start learning another one.
Hope this helps! Good Luck!
Start your own portfolio:
-you can showcase all the projects you have worked on
-get experience with git version control
-search other public projects
-add this to your resume and future internship/job applications
Hands on experience with coding, participate in lot of coding challenges would give additional advantage.
Java with Spring is a good option
Pick a language (any popular language) like others said and make something, a little script, a small program, whatever. You will learn a lot by trial and error. Then rinse and repeat with another language and you will notice patterns in how things are structured. This is especially true in languages that share the same syntax heritage. Most of all have fun learning and don't stop learning. The most successful people are those that don't stop learning and have a growth mindset.