Congrats!
I
F is the maximum
Forward current. The one you need is the I
Z, the Zener current, which for a 12V BZX55C is I
Z=5mA, much smaller than I
F=200mA.
The current limiting resistor should be 7V/5mA=1k4, maybe smaller if you consider the current drawn by whatever circuits is powered from the voltage stabilized by that Zener diode.
Beware that the range of current variations in the load should be much smaller than those 5mA of the I
Z, or else the load will influence the functioning of the Zener. If the load needs more current, then you'll have to add a simple voltage follower with a transistor, or something else that can stabilize bigger currents.