FL studio is the easiest to learn and easy to acquire especially for windows users. Audacity is okay for dealing with audio but in terms of composing you’re not going to get anything out of that. Its a good tool to play around with if you want to play around with some recording and dealing with audio files.
I used to make beats and used primarily logic but it isnt free and theres a bit of a learning curve that goes with most of the DAWs such as Reason, Pro Tools, etc.. Unless you throw in some big bucks the plugins sound quality wise are not good unless you learn enough to know what to adjust for parameters. FL fortunately has some decent start up plug ins where getting decent sounding synths isnt hard and the drum packs are easy to clean up.
I would start off with whatever program works for you a small midi device, can be a keyboard, mpc, whatever really, and decentish pair of headphones. Its affordable and you can fool around learn somethings before putting down any sort of investment into equipment. I can provide more advice later but thats kind of the basic basic to composing at least hardware wise.