If you mean an NPC moving, and when you stop her she talks then;
For the message, follow the same as if she was standing still;
Action Key
Message : Blah blah blah I can talk w000t
However, you should notice a box on the event page saying Movement Pattern
Select a type, random or user defined. Random means she'll walk anywhere, user definded means shell walk the way you program her too.
And its as simple as that!
If you want her to stop after youve spoken, make a new page, and just put no movement on the movemt pattern, simpla!