If you can receive any OTA digital TV channels you can use the following procedure.
The 'Frequency correction is the 'ppm' on the Configuration pop-up window.
It is used to correct the frequency variation of a particular dongle. (They all vary)
Typically, once it's set it doesn't vary much from day to day. But you must do it after the dongle has been powered on for a while.
Then, every time you start it up from cold, it will take a while to settle back down.
There are several ways to find that correction. (after about a 30 minute warm up).
The easiest way is to use the 'pilot' of an ATSC TV broadcast.
That is supposed to be 'exactly' 310 kHz within the TV signal. (ie. Channel 14 is at 470.310 MHz)
Using the highest frequency local channels works the best.
You can see a list of them here. Just check against a few local TV signals because they DO vary slightly.
North American television frequencies - Wikipedia, the free encyclopedia
Rich
Edit: This shows the view while calibrating to an ATSC TV pilot frequency.
Notice for best accuracy you need to zoom in.