Drag is the only force that can slow an airplane down.
There is the drag due to friction and the drag due to lift.

There is nothing you can do about the first type, since your plane has no flaps to deploy and no ailerons to perform a slip.
However, you can increase the drag due to lift via elevator control.

More elevator up produces higher wing's AOA.
Higher AOA produces more lift at the same speed or the same lift at slower speed.
Slower speed is what you want.
Critical AOA is the limit to that trick.
Critical AOA is the maximum AOA that your wing can take before stalling and loosing substantial amount of lift.

Just feed elevator gradually while you reduce throttle.

Practice stalling the wings high enough.
Get familiar with the max AOA and minimum speed that are safe for a regular landing.
Below the critical AOA, your elevator is your brake.

In a step dive, height becomes speed; hence, descend slowly.

Your plane has elevator and rudder only; hence proper aligment is key in order to avoid dramatic maneuvers when your plane is slow and low.

Read this article:

http://masportaviator.com/2004/01/17...ng-techniques/