Does all the alphanumeic LCD modules have backlight? and where can I find LCD commands for this module?
Backlight on most character lcd displays are independent of the lcd. Typically, if included, has a backlight Anode and Cathode pins. There are many without backlights at all too. The pins/pad will be there, but the hardware for the backlight might not be populated. Most manufacturers use a standard pcb which they customize as needed.

Based on your generic pinout/wiring, and since you got it working with a code sample, it's a fairly safe bet that it uses the nearly universal HD44780 alpha-numeric dot-matrix character lcd driver compatible code set.

HD44780, KS0066U and SED1278 are mostly interchangeable.