Assembly of blocks in Auto CAD by Accessing Block library

Hi,

I have CAD library & wpf contains some combo boxes for getting the input from user.if user clicks any of the item in combo box then the Auto CAD should open ,the selected block will be get from library and lie in Auto CAD.How can i do that?

 

For Example,

I have a  CAD Block library ,the block contains Model 1,Model 2,Model 3,Model 4.

if any of the model selected in combo box then the Auto CAD should open and respected model should be selected from block library  and Assemble in newly opened Auto CAD file.

How can i do that?