How do I know if my phone is Factory unlocked?

It is locked to Bluegrass cellular. They do not offer unlocking. The only source for unlocked iPhones in the US is directly from Apple.

Just Put a SIM from another carrier in it and then Reset network settings: Tap Settings > General > Reset > Reset Network Settings.

if its working then its unlocked otherwise,,,

Bluegrass is a CDMA carrier, so yes, all their phones will be effectively carrier locked to their CDMA network (CDMA phones are locked to their carrier in firmware, as all network connection settings are stored on the phone itself, not on an external device like a SIM card).

There is no such thing as a "factory unlocked" CDMA iPhone 4S, never has been. All iPhone 4s's sold directly by Apple as unlocked were GSM models.