OK. Backstory first: An hydrometer provides information about the density of a liquid and wine makers use the density as a measure of the sugar content. The greater the density, the more sugar is in the must (fruit juice). The greater the density of the must, the higher the bulb at the bottom of the hydrometer will float and the lower the density the lower the bulb will float. Knowing that, the manufacturers of hydrometers etch lines on the stem that provide you with an idea of how high or how low the bulb at the bottom is floating. If you placed your hydrometer into a jar filled with distilled water the line at the surface would be 1.000. Water with added sugars would make the bulb float higher - 1.010, 1.040, 1.060, 1.090... the higher the number , the more sugar in the liquid. You can think of those numbers as "points" (so , 10 points, 40 points, 60 points and 90 points of sugar)
The readings you have are a little above 1.100 and so you have about 100 points of sugar from the grapes. If all that sugar fermented dry (to alcohol and carbon dioxide) your wine would be about 13% alcohol by volume (ABV). I cannot say whether you need or want to add any sugar because I don't know what ABV you were aiming for but IMO, a wine with 13% ABV is right on the money.
As the yeast converts the sugar to alcohol, the density will drop and so your hydrometer will slowly fall lower and lower into the liquid until the reading is at 1.000 or even lower (alcohol is less dense than water) so an hydrometer placed in a jar of dry wine might provide a reading as low as 0.996 - only an inch (a couple of cm) or so of the top of the hydrometer would be above the surface of the wine.
Hope that this helps. Good luck!
