How Do I Insert A Render To Me Photoshop

i cant do it i cant find the button

 

create a new document say 400x150 and open up a render and select teh arrow and drag it into the 400x150 document

 

the button is called open file...

 

just open the render and drag it to the sig or whatever your using it for

 

Instead of dragging just open it then go to select -> all then edit -> copy then make the document for your sig and paste it.