Hi and welcome here.
How much knowledge do you have from before?
You're going to need to learn at least the basics of: music theory (chords, harmonies, scales) and then apply that knowledge in a DAW (digital audio workstation) that you choose. Then you need to learn about EQing, Compression, Reverb and delays etc. If you're a beginner with any of the effects then you'll probably overuse them in the beginning so some time of training is definitely required.