So I wanted to make some minecoins and I also heard that anyone become a marketplace creator could but I don't know where to apply. I'm in Minecraft Pocket Edition 1.14.30. Can you tell me where I can apply?
You must be part of the Minecraft Partner Program. On this page, you can apply.
Keep in mind that demand to be a partner is very high; it is common to have to wait several months to even hear a reply. You also must show that you have the skills to create content, such as a portfolio of existing creations (worlds, skins, etc.) that you have personally created.