The first thing is, it must be Febreze. Remove the empty glass air freshener canister from the air effects plug in. This is a two sided container, with two white wicks sticking out of the top. These are caps that cover the liquid air freshener and hold the sent.
Next, take a pair of pliers and grip the middle of the wick. The gently wiggle back and forth while pulling upward. Try not to bend the wick. Be careful and do this gently so that you do not remove the wick from the cap. The wick and the cap should pull off of the glass container, leaving you with an open hole.
Repeat this step for the other side as well. Now you have two open holes on an empty container. These holes are about the size of a dime. They are large enough to pour liquid into.
Next refill the container with you favorite sent. I used vanilla and almond extract diluted with a little bit of water.
Replace the caps/wicks back over the container holes. Place the air freshener canister back into the plug in and plug it in!
That's it. You have refilled your air freshener for not a lot of money.