How can I add BLOCK in my_controller Dynamicly?

I was trying to offer all the Custom_Queries in the combox of myPage.
It relates the BLOCK of my_controller,
my Question is :

How can I add BLOCK in my_controller Dynamicly?
(the name I was trying to add into the BLOCK was not sure,and the template I was trying to render is the same one )

thanks for help....