namespace name 'Fireball how can Add please sent link...

Question

hi experts..... 
Which reference should i need to addd for using "using 
Fireball.Docking"..when i use this code it s an error.I am using visual studio 2008.
   or

how can add  to the  namespace name 'Fireball' could not be found (are you missing a using directive or an assembly reference?) 

   Please help me....