Hi Karey. Are you talking about the bridge plate? Could you possibly post a picture? Setting the bridge plate is part of the setup. Some players like it floating (not parallel to the body), so they can use the tremolo (vibrato) arm to raise or lower the pitch. Others (myself included) prefer them "decked" or flat against the body. This doesn't allow you to raise the pitch with the tremolo, but you can still lower the pitch. Still others lock it by putting an obstruction in the back of the body to lock the bridge.
Also, does your Strat use the vintage style bridge plate (6 mounting screws) or a 2 point bridge?
You can "deck" your bridge by removing the back cover and tightening the two screws into the body that hold the claw. But on most bridges, the saddles are very nearly at the pivot point. You won't get very much change in string height. String height, while partly a function of the bridge plate position is usually controlled by raising or lowering the actual saddles under each string, using an Allen (hex) wrench.
I see you have the Alfred's book. You might also want to snag a copy of the setup information directly from Fender. This is one of several things I keep as a reference and used to learn how to do setups. You'll find it here:
https://support.fender.com/hc/en-us...-do-I-set-up-my-Stratocaster-guitar-properly-