They do have answers on their website, you may want to check your printed or online crib instructions to remind yourself how you put the crib together, too.
I found the answers here:
i've pasted them below. You can make it a toddler bed without a side rail just by removing the movable side of your crib, and you can install the side rail instead of the movable side if you want it to look a little more finished and help keep your child from rolling out of the bed.
How to convert a crib into a toddler bed
convert a crib into a toddler bed you must loosen the two front gold
bolts left and right side of the crib and remove the dropside (the
front gate that goes up and down). After removing the dropside be very
careful that you tighten back your two gold bolts. How to install the streight rail (toddler rail)
To install a streight (toddler) rail
loosen the two front gold bolts left and right side of the crib and
remove the dropside, once you have removed the dropside replace with
the streight rail. Always be very careful and make sure you tighten
back your two gold bolts in the front.