Install the blinds over the window as directed by the product directions. Lower the blinds all the way. If your blinds are already hanging, proceed to the next step.
Find the plastic plugs on the bottom side of the last slat or bottom rail. Pull the plugs out of the bottom rail to release the string ladders and the lift cord.
Locate the knot in the lift cord. Untie the knot, then pull the lift cord to allow enough slack in the line to remove the slats.
Take out the bottom rail and enough of the lower slats until the blinds are the length you want.
Replace the bottom rail so that it is the bottommost slat again.
Trim the string ladder below the bottom rail with scissors so that about 2 inches of string hangs down. You will need this extra string to insert in the bottom rail's plug holes.
Thread each of the lift cords through the holes in the bottom rail. Make sure the lift cords are even, then tie knots at the end of each lift cord so the bottom rail stays straight.
Tuck the ends of the string ladder into the plug holes in the bottom rail. Insert the plugs back into the holes. Gently tap the plugs into place with a hammer.