Can you import musical instruments such as violin, piano, horns and where would you get them?
I found the guitar “pluck” sound but no keyboard or other sounds i can use to compose music.

Composing in Audacity would be extremely frustrating to the point of being impossible. Generating all the sounds at all the frequencies at the various lengths and then stringing them together would take forever.

You want a MIDI composition program, which Audacity is not.

Are you on Mac? If so you should give GarageBand a try.

– Bill