Have you ever tried to find a cemetery where ancestors were probably buried, but it's not on any map you can find? The road may have changed. The cemetery may be in a field somewhere, hopefully fenced in somehow, probably overgrown with weeds and brush. But where is it?
Let's use this as an example. After you've entered what you know into the form, you'll get something like this:
PLOT THE MAP:
Likewise, along the top and/or bottom are the tiny Longitude numbers, 88W and 89W in our example. Our cemetery is farther west than 88 degrees, but not as far west as 89 degrees.
And now you have a little imaginary square and the cemetery is right in there somewhere.
For our purposes, we don't really need to be as precise as the data given. It's enough to know that the cemetery is a little over half way between Latitude 32 and 33 (5917 is roughly 60% of the way). So with the Longitude, 4107 is only about 40% of the distance from Longitude 88 toward Longitude 89. Get the idea?
People who live in that neighborhood can probably help you find the exact spot. Maybe the County Agent could help or one of the local Pastors. And of course, there are always our friends at the local Historical and Genealogical Society.