How to make custom effect with icon ?

[FLUFFLE PUFF]

Here is my code:

public static final DeferredRegister<Effect> EFFECTS = DeferredRegister.create(ForgeRegistries.POTIONS, Bettermushrooms.MOD_ID);
public static final RegistryEvent<Effect> CUSTOMEFFECT = EFFECTS.register("CUSTOMEFFECT", () -> new Effect(new EffectType().));    <-    here is error

[FLUFFLE PUFF]

Cannot instantiate the type EffectType

[FLUFFLE PUFF]

nothing , i did not find any information about "how to make custom effect"

[FLUFFLE PUFF]

ok , thanks .  but how to set an icon for effect?

[FLUFFLE PUFF]

thanks 

[FLUFFLE PUFF]

I have another question , how to make screen warp like in nether portal and how to connect this screen warp to my custom effect.