Can you put your question more clear?
However I will try to answer with whatever I could make out from the question.
There are mainly two coloured lights in the CPU cabinet which we can see. The colour sequence cn change as per how they assembled it. Some computers have green for power indication and red for activity indication.
The first one on staring is the power on indicator .
When the computer is started by putting the switch on after plugging into the main power supply plug or board, we get a power on indication. Then the computer parts inside get powered on and the hard drive starts its work as per the default procedures. The hard disk activity can be seen by a blinking red light.
In your case it appears that the power on LED is not working. But the activity indicator light is working.
So if your computer works fine after plugging the power chord(plug) and switching on, then you need not worry. In case the computer is under free service period you may get it rectified from the vendor. But if you feel it is some problem to you, you may contact the service person and get it rectified.
You should disconnect the power chord only after properly shutting down the computer and putting of the plug switch.