Philip Persio AlarmCHRONO TITANIUM 90aam0606 - Philip Persio AlarmCHRONO TITANIUM Watch

It should be SOLID TITANIUM Screw down case back.

GoAir Customer Care Number

LUN is short for "Lunes", spanisth for Monday. You will probably have MAR for Tuesday, MIE for Wednesday, JUE for Thursday, etc...

usually you can find it where you buy your watch.. maybe in the malls

all dealers have em

http://www.oakley.com/dealer

many of these watches require 2 batteries. One for the analog and one for the digital. I would contact a jewelry store to make sure they will change your batteries; since the watch was free to you it will surely be worth the price of new batteries to get it working.
Also, some models do take only one battery but if it is not at a full charge you may have the issue you described.
If not a battery issue, then there are other detailed steps to follow (the jeweler should be able to help you.)
Note: I recommend contacting an independant jeweler (non-chain and non-mall store) because most non-independants will not change batteries in watches they don't sell.

Take off the back of the watch. If the weighted wheel on the back is loose, tighten it carefully with a flathead screwdriver. If it's already tight, then you may need to dig deeper to find the problem, possibly located at the spring. I would recommend taking it in to watch repair if this is the case!

On mine the back turns off using the notches in it. I persuaded it with a small screwdriver. Just be careful it doesn't slip and hurt you.

Yes, your watch is battery driven and you may need a battery replacement.