Can someone please please explain the difference between long and short vowels..?
The OE vowel system carefully distinguished between long and short vowels. Distinguishing between long and short vowels can be difficult at first. Scottish speakers may notice a quantitative distinction in their pronunciations of the stressed vowels in GREED and AGREED; many English speakers might compare their pronunciation of GRID with GREED (although the quality as well as the quantity of these latter vowels differ). Many teachers of the subject regard the distinction between short and long vowels as unimportant for the beginning student, but it is useful to know about them when you move to more advanced philological work. Thus, although you will not be required to insert length-marks in the Exercises, length-marks are given throughout. Some examples of the difference of meaning length of vowels can make in OE are: God GOD and gōd GOOD, wendon TURNED and wēndon BELIEVED, āwacian TO AWAKEN and āwācian TO GROW WEAK.
