you have to beat team rocket in Lavender town first. after you do that, go to the building entrance. the "guard" will be asleep, allowing you to get in. again, like i always say before these mimi-quests, STOCK UP ON ITEMS!!. you can also find some items in the building, so deposit any items that are not necessary (ex. any elemental stones, stardust, nuggets, you can find those in the building), but keep healing items (ex. lots of potions, elixers, ethers). when you get to the top of the building, you will fight Giovanni, team rockets leader. make sure you heal your pokemon first, he's pretty strong.
