My mod won't load.

Hello guys,

I'm making a mod and I want to test it out so I did the action "build workspace" and did the "run client", but when my minecraft opened, my mod wasn't working. The client was opening but my mod didn't load. I tried to export it and to put it into a curse forge modpack on my own and the folder didn't "detect" my mod. My mod was in a jar document so I don't really know why it didn't load up. Any idea?