Sound design vs. composition
Sound design and music composition are not the same thing, but it's easy to get the two mixed up. Current tech makes it so easy to play with sounds, you can sound design for hours without actually writing anything.
So, I would suggest doing the opposite in your writing process:
First, focus on writing interesting musical ideas that work well together, using whatever simple instruments you already know how to play. Don’t get overly distracted by finding tones too early in the writing process.
Next, once you’ve settled on some musical ideas that work well together, start experimenting with tones and instrumentation.
If you focus on finding sounds too early, you can get lost in that and it can be hard to learn how to write well, or to finish your musical work. I see many students get frustrated because they've spent months clicking around inside a computer program tweaking sounds, without actually writing anything they like. We don't want that.
Keep the technical side simple
Using simpler recording techniques can help you stay focused on the composition. Sometimes, writing using just a guitar and a simple digital recorder (or the voice memo app on your phone) works better than starting out on the computer.