My dead eye is not working online

Goooooooooooooooose
Online you don't have that ability to begin with. You need to upgrade a special ability card.
The card is called "Paint it black". It can only be selected in the first active ability slot. The remaining slots are for passive abilities.

Voidear
thanks

Goooooooooooooooose
Then poke the middle mouse button (wheel) and paint, you can use guns, it doesn’t work with a telescopic sight! Also, you can’t color a player who has the protective mode turned on! You can even shoot birds, with a good rifle you can paint the whole flock of ducks =)