Adding a new map service layer by code HTML5

I need help for how to add a map service to the layer list using code so the user can interact with it through analyze and all of that. 

 

The use case is the user does a query on a map service using a form and then the results need to be added as a dynamic layer to the layre list. We had this working in Silverlight and also had it working in HTML5 2.4 viewer but it was likely hacky code. 

 

Can someone provide some guidance here please?