How do I play the animations I made using animator?

First off you would need an event telling you when they've said "/e breakdance" which you can do via the .Chatted event. For example:

game.PlayerAdded:connect(function(plr)--Fires when a new player joins
    plr.Chatted:connect(function(msg)--Fires when the new player chats
        if string.sub(msg, 1, 3)=="/e " then--Checks if it is a command
            if string.sub(msg, 4, string.len(msg))=="Command" then--Checks what command was said(Change "Command" to breakdance or whatever you want)
                print("The Command goes here")
            end
        end
    end)
end)

Now you just need to make the character dance which can be done by creating an animation object and play it. Here's an example:

local BreakDanceAnimation = Instance.new("Animation")
BreakDanceAnimation .AnimationId = "http://www.roblox.com/Asset?ID=173766787"

local animTrack = plr.Character.Humanoid:LoadAnimation(BreakDanceAnimation)
animTrack:Play()

That's all it should take. If you need more help I suggest looking at the wiki article.http://wiki.roblox.com/index.php?title=Animations