Please go to this site and read it carefully. It will help allot. The Drum Dial is no help until you do a little studying about drums. This guy had similar questions to yours.
I found this by Mr. Der Trommler, it's a post from February. This guy had similar questions to yours:
"I will try to run through this and answer some questions. The top head is called the batter head and the bottom is called the resonant head.
Typically you would want to use a resonant head that is matched (or designed for use with) the batter head. (Keep in mind that this is not set in stone, I know drummers that mix head manufacturers to get the sound they desire and that is ok too).
Typically you will want the batter head slightly tighter than the resonant head but that varies with head type and desired sound (or what you think sounds good).
If you are playing casually and your kit is inside of a temperature controlled room all the time, then you can get away with changing the batters once a year to year and a half, and the resonants every couple of years unless they become damaged in some way (dimpled or ripped). You might want to change them sooner than that if you notice the heads won't hold their tune.
Here is a link to the Drum Tuning Bible which will help you to understand heads and tuning much better:"
Drum Tuning Bible
Please check out this video too, this should help allot and with all this information you should solve all of your questions about your drums.
Changing & Tuning Your Snare Drum Heads