Hi, I'm Bill Walker, and I'm here to show you how to shorten Venetian blinds. You will need a pair of scissors, and a flat headed screwdriver. The first step is to mount the blind into the window. Lower the blind down, past the windowsill. The next step is to determine the number of slats to remove. For instance, if there are four slats that are hanging down the sill, then you will want to remove them. Next, remove the tape buttons from the bottom of the rail by gently prying them off with a screwdriver. Cut the lift cord away from the bottom rail. Pull the cord out of the slats you need to remove. The slats will sit inside a corded ladder. Remove the slats from the ladder. Straighten the lift cords back through the bottom rail hole. Now, tie a knot in the lift cord. Make sure it is big enough, so it will not come back through the bottom rail hole. Lift the blind, and check to see that it is parallel or even with the windowsill. If it is not even, you will have to adjust the length of the lift cords. Do this by retying the knots. Now you can cut the excess length of the ladders, and put them back into the holes in the bottom rail. The last step is to replace the tape buttons into the holes in the bottom rail. The buttons will hold the ladders in place. And, that is how to shorten Venetian blinds.