Q: How to add particles?
A: Its very simple. When you place a chest on top of the block you set in crates.yml the plugin will automatically add its coordinates to the blocks.yml file. You will just need to restart the server for the particles to show.
Q: How to remove the particles?
A: Just destroy the chest whose particles you want to remove. Restart the server and the particles will be removed.
Q: Will the crates have floating text above them?
A: Yes, they will have Floating Text.
Q: Can I edit the floating text that appears above the crate?
A: Yes you can. Navigate to blocks.yml and edit the crate text you see. For example, you want to edit the floating text of legendary crate then there would be a key\heading of legendary: in the blocks.yml file. Edit the text after the : to edit\change the floating text.
Q: I found a issue in the plugin what do I do?
A: Please open an issue here and give as much detail as possible.
Q: I would like a new feature to be added. How do I report?
A: Enter the feature in #34. Give as much detail as possible and I will see what I can come up with.
Q: What to do with the blocks.yml file?
A: You need not to do anything with it unless you want to edit the floatiing text. The plugin automatically generates stuff within the file to make the setup for the user easier.
Sorry but I don't understand what you are trying to say. Anyway if you want a tutorial on how to setup MysteryCrate then my friends over at server.pro have done an in-depth tutorial on how to set it up. You should consider watching this https://www.youtube.com/watch?v=dnUkjgA2v1k