Answer:
some websites i use with my school and at my company are really good. Although lots of them require you to buy instruments to make the music, the websites i use are don't always need these instruments, but have online tools to use on these websites.
soundtrap is amazing, and it was great when i first started composing, its very self explanatory and great for people who just started. this one is free
ampedstudio is a great on that I use the most now, while having instruments is great for this one, you can still use it without instruments. Its great for transmitting the songs to other people and publishing it, this is always free.
While people dancing is great. sometimes that kind of song is not great. the beat will override the lyrics, therefore putting your work into the message, and lyrics to shame.
A sad song will be good if you make it into a hiphop song or rap song good references would be NF's How Could You Leave Us and Stray Kids' Side Effects.
A mad song will be bad because most people will hear the anger and turn away immediately because they will feel attacked by the sudden anger.
hope this helped mate