Written language is only an approximation of spoken language. You can see why we can't quite deal with phonology with regular written alphabets. It's a lot of fun and quite valuable to linguists, but it is only loosely connected with grammar, so we won't often mention it this term. Morphology is the study of basic meaning-bearing units in a language. Sometimes you would recognize these morphemes as syllables or entire words.
Morphemes are slippery critters sometimes.
As usual, you have little to learn here. The list of actual inflectional morphemes is brief. In fact, the ones you just saw in this paragraph are just about the whole story except for some variations in spelling. That's mainly what we are studying this semester. I won't go into it here.