Moving a servo a set distance using a push button, then when released returning

Ok so I have been wanting to get into Arduino coding and am as green as anyone could possibly be to it. I am making a Rube Goldberg machine for an engineering class but want to incorporate an arduino step in the process. Basically what I need is to have a micro switch or push button sweep a servo arm a pre determined set of degrees, but when released return the servo arm to the zero set point. I completely understand how to use a pot to sweep a servo but not understanding how to create set angles with a HIGH/LOW input. If anyone knows of a good starting point for me or possibly has done this already any help is greatly appreciated. Also I am a very visual learner so if you know of any schematics for the setup that also could be super useful in my endeavor. Thanks in advance for all the forums helpful members.

It could be something as simple as this pseudocode:

pinmode the button with pullup resistor
read the button
if (button is pushed)
..... servo write to one angle
else (ie, the button's not pushed)
..... servo write to another angle