Registering

In the main class...

In your main class, we have four things we need to register: The block, block entity, the recipe and the screenhandlers. To do this, go to your class that implements ModInitializer, go to onInitialize() and add this if you haven't already

@Override
public void onInitialize() {

    ModBlockEntities.registerBlockEntities();
    ModBlocks.registerModBlocks();
    ModRecipes.registerRecipes();
    ModScreenHandlers.registerScreenHandlers();
}