Tip: Remaking levels from other Mario games is strongly discouraged, especially popular ones (World 1-1 from SMB or SMB3, for example), as their over-presence in Mario games, official or not, often makes them uninteresting to play.
Over the course of the past few years, in order to help others with learning ASM, I've continuously worked on and released my SNES ASM tutorial. Nowadays, I have two ASM tutorials, one focused on opcodes and one which gets you started with ASM hacking. Feel free to check them out!
If you want to edit my submissions, you have my permission. In fact, you can even submit them back to the Central. It'll simply mean more (improved) resources for the hackers out there which is a good thing. As of 2020/07/27, rule C6 has been added. I am hereby granting explicit permission to others to modify my resources, as long as I am credited. I am pro-open source resources, after all.