You might need to dig a bit more in the instrument setting screen, some of the sounds could possibly use some finessing.
I'm not sure if you consciously left out any bass line or if you intended to put the melody/harmony so close together sonically; for me the similar timbre and closeness in register makes it hard to distinguish them. That said, you've clearly got a hold of the basic operation of the software and how to put together a song so you can start to really explore now.
There are a million tutorials on how to use LSDJ so I'm not going to bother giving you any of that because, really, LSDJ is easy to learn compared to learning how to write a good song. Teaching someone how to write a song is hard for even a professional music teacher and I'm certainly no expert in that regard but I'll give you the best advice I can give to someone who is learning to write music:
Your first focus should be listening to a lot of music. Now that you're writing music you need to start to listen to music in a different way. Normally your brain takes all the information in a song, answers a bunch of pretty complex questions totally automatically and then returns to your conscious brain the answer to "is this a good song". Now that you want to start writing good music, you've got to start training yourself to answer those questions...erm, yourself?
When you hear a song that you really like - or one that you hate, because you can often learn just as much from that - you have to really listen for what's going on. What is making that song so interesting or catchy or awful? What do you like about it? Listen to each element, start isolating each of those sounds in your head and listening to what they're doing. Where do they sit in the register - are they sitting in lower octaves, near the middle, high up? - and how the the different instrument's timbre interact with one another? What is is about the timbre of a sound that makes it sound evoke a given feeling?
What about the arrangement of the notes; what makes a fun melody, what makes a sad one? Why are some melodies catchy and others cheesy and how can cheesy sometimes sound perfectly catchy? It's not just the pitch of the notes, what the meter like? How long is each note, how long are the rests between notes? Some of this comes down to music theory but scales on their own are boring, a huge part of music is about expectation and surprise - patterns and change - and the interplay between them. What do these different arrangements make you feel? That's always an important question to ask about any given musical choice; what emotion does it evoke? Don't restrict yourself to "happy" or "sad", there are a lot more colours to paint with - silly, wistful, sly, angry, creeped out, sexy, snake-like, joyful, playful - there are a lot.
Starting to answer these questions for yourself is really important and I can't really answer them for you - partly because I don't know anything about your musical background, what you enjoy listening to or what you are trying to create - but also because your unique answers to these questions are what will define your own personal aesthetic. The music that you make will be strongly tied to your personal taste and really the term "taste" is just a fancy word for the sum of all those answers that your brain normally makes automatically.
