Cmos battery failure shows on display

[munda12]

When i start my computer having windows xp software it shows me the firmware detect cmos battery failure. please let know the solution for this.
It will be your most kindness.

 

[LucaFire]

This means that you should replace the small, silver battery on the motherboard with a new battery.
You can buy one here at Newegg: https://goo.gl/3BAmXV (This is not the cheapest one, you can look around by searching in any technology store "CMOS battery")