LMMS is an open source software. Recommend.
There are many LMMS tutorial to get you started, and of course like all software, there are help manuals.
Just experiment, and create 'sound' that you your self enjoy. Or create your 'vision' (sound vision) of what a track should sound like.
LMMS already comes with 'tons' of instruments/synthesizer. It's not the end all be all of course. For starting out though, I highly recommend it. As it'll take you very far.
That's the software itself anyway. Learning more about music will help as well. Just experiment. As creating music is it's own skill.
If you'd like to learn how to create music itself, then seek out those resources. As without that, even with FL studio or more standardize software, you'll still be limited to your musical knowledge.
It's like you can get the best typewriter there is, but without learning how to write as a skill itself, the typewriter at the end of the day is just a simple tool without expertise.
