I need scripting help (H5)

[Jikarosa]

Hello! I am new in this forum and I did actually join here because i have a question for a problem I can't solve:

I'm doing an multiplayer map that contaisns several scripts. I have made an object that should work as Death Knight dwelling. So i need a script that tells player who interacts with object that: "You can recruit Death Knights here for a price of 2000 gold coins and 1 mercury." Then player is given a choise to pay or refuse.

If player refuses the message box disappears, but if player pays, 1 death knight will be added to hes army.

Can anyone help me with this?