I tried everything and still it does not work... https://paste.md-5.net/pucopakofa.http (btw I used two spaces instead of a tab) In the first paragraph you can see a plugin.yml file and in the second paragraph you can see Main class, and in case I uploaded code in the third paragraph...
it shows me this:
org.bukkit.plugin.InvalidPluginException: main class `org.emisdevs.ChatCommand.Main' does not extend JavaPlugin
at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:73) ~[spigot.jar:git-Spigot-db6de12-18fbb24]
at org.bukkit.plugin.java.JavaPluginLoader.loadPlugin(JavaPluginLoader.java:131) ~[spigot.jar:git-Spigot-db6de12-18fbb24]
at org.bukkit.plugin.SimplePluginManager.loadPlugin(SimplePluginManager.java:329) ~[spigot.jar:git-Spigot-db6de12-18fbb24]
at org.bukkit.plugin.SimplePluginManager.loadPlugins(SimplePluginManager.java:251) [spigot.jar:git-Spigot-db6de12-18fbb24]
at org.bukkit.craftbukkit.v1_8_R3.CraftServer.loadPlugins(CraftServer.java:292) [spigot.jar:git-Spigot-db6de12-18fbb24]
at net.minecraft.server.v1_8_R3.DedicatedServer.init(DedicatedServer.java:198) [spigot.jar:git-Spigot-db6de12-18fbb24]
at net.minecraft.server.v1_8_R3.MinecraftServer.run(MinecraftServer.java:525) [spigot.jar:git-Spigot-db6de12-18fbb24]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_241]
Caused by: java.lang.ClassCastException: class org.emisdevs.ChatCommand.Main
at java.lang.Class.asSubclass(Unknown Source) ~[?:1.8.0_241]
at org.bukkit.plugin.java.PluginClassLoader.<init>(PluginClassLoader.java:71) ~[spigot.jar:git-Spigot-db6de12-18fbb24]```