First off - the manual is WAY to comprensive to read for a mortal. I'll see if I can dig up the note collection my teacher gave us for DSP class, it had screenshots and nice things for teaching us to use the basic functions.
the MEM key is set "2nd" so you need to hit the yellow "2nd" key first (hint - the yellow texts above the buttons need "2nd" the blue needs "alpha" to be hit first - the ones printed on the are the default actions)
replace your 83 with a 89 or 92 model it's much easier for a beginner to understand the visuals on those models when it comes to fractions etc.
I only have the 85 and 89 models so my directions are based of those models - they are true graph calculators I dunno about the 83.
Does this mean you are finished being a troll towards me and that you are very sorry?