Here's a picture of what the stock cover looks like:

If you lift the brake up as high as you can, you can get the small plastic pin out with a small (eg jeweler's) screwdriver. Then pull out the other section, unscrew the knob on the end and then you can slide off the handle by pulling it forward. Then you'll have:

and you can put your new one on.
Hope that I understood what you were asking and that this helps.And welcome to the forums.