It should come with small plastic hoses. Before it goes in the truck, fill resovoir with fluid, connect the hoses to the MC and put the other ends of the hoses into the resovoir. Pump the end of the MC with a screw driver or whatever fits into the end. Keep pumping until all the air is gone. When you install it into the truck, bleed all the brake lines. If you are not sure you can do all of this, get someone that knows what they are doing. No brakes can be very bad.

A new MC should have instructions.
Be careful with brake fluid, it likes to take paint off of stuff, including your Montero.