Its better than what i started making. I also have not learned music theory. I just listen to the music i like and take inspiration from it. You can import SFX or instruments as long as they are .wav files
#First attempt
summer coral
simple holly
damn for a first try this sounds pretty decent tbh!! ofc some things could maybe feel off for some people but it's really not bad for a beginner really :D i like it
you could maybe make it less repetitive by switching the melody from times to times idk
as said above, you don't really need music theory to make music. ofc it will help, but it's not necessary. if so, i think you should find plenty simple theory tips here and there on internet. there's a youtube channel i really like called synthet which have a big range of small tips and tricks to offer (for fl studio, but they can also be applied to lmms)
it's not really music theory but it's a lot of useful little things for music producing on computers
for the instruments you can get free wav files pretty much anywhere on the internet (imo it's especially cool for drums or sample loops), but if you want to make your own melodies etc i think you should look for plugins call vst2!! those are instruments taking the form of .dll files which can be played in the VeSTige stock plugin from lmms, really it's a game changer imo and you can easily find plenty of free quality vsts around the internet (it shouldn't be too hard to find a piano for exemple)
there's also .sf2 files you can use, you can run them in the soundfont 2 player stock plugin
the quality is really not the same imo, but you can still do a lot with sf2 files
(hope i didn't drown you in advice, if some things seem unclear don't hesitate to ask for precisions 😭)
simple holly
np, have fun in your music journey!! B)