You need the Spikey Eared Pichu from an event. You then need to take it to the Ilex forest shrine, Celebi will then appear and transport you to the past where there is a short story to follow.
However, I'm not sure if you can catch Celebi at the end of this.
You might want to try the Global Trade Station
It is an event
Im sorry to say but you can not catch the legenedry celebi in Pokemon heart gold but you can get action replay and type in the code for action replay to catch celebi or you could go to the next celebi event
You can't catch it.
well you cant catch it in Pokemon white you have to get it in Pokemon heart gold or soul silver using an event IF YOU ONLY WANT CELEBI WELL YOU CAN ALSO GET ZORUA IN CASTELIA CITY WITH CELEBI SO ID DO THAT ONCE YOU GET CELEBI
no. you only can get celebi in emerald, sapphire, and/or ruby.
There are only a few you can catch but the rest you have to get from trades with other games.
you first catch celebi
Celebi
It's the pokemon, Celebi.
You can catch Suicune, Entei, Raikou, Lugia, Ho-Oh, Celebi, and Mewtwo, Moltres, Zapdos, and Articuno.
You can only get it through Nintendo events. (Sorry:)
You need a fateful encounter one