First off if you're a noob- you're doing great to even make it up a hill like that and get major points for having it as a part of your regular commute- that's a tough hill.

To know the size of your cassette you simply have to count the "teeth" of the largest of the rear gears and the smallest gear- this will give you the range (ie. 13-32). The front two (or three) "chainrings" are usually marked with the number of teeth on the chainring itself (ie. 52/39). This gives you your gearing depending on what combination of front chainring and rear gear you are riding (ie. 52 x13 or 39 x 32 or anything in between). The formula of front chainring/rear gear/and tire size gives you the gear in "inches" (ie. a 100" gear), which is the distance you'll travel with one revolution of the pedals. The higher that ratio the harder it will feel to "push" that gear because, naturally, it takes more energy to move your bike and body 100" with one revolution of the pedals than it does to move it 32".