need to change dell 3537 key board to backlight keyboard

Solution
Different model but still an Inspiron 15 series like yours: http://www.tomshardware.co.uk/answers/id-3021629/replace-dell-inspiron-3531-backlit-keyboard.html

It's likely some cabling will be missing in your model to power the illumunation. You won't know till you remove existing keyboard & order an illuminated one, so myself I wouldn't risk it unless you can return new keyboard for a full refund (component suppliers usually charge for returned goods which aren't faulty).
Different model but still an Inspiron 15 series like yours: http://www.tomshardware.co.uk/answers/id-3021629/replace-dell-inspiron-3531-backlit-keyboard.html

It's likely some cabling will be missing in your model to power the illumunation. You won't know till you remove existing keyboard & order an illuminated one, so myself I wouldn't risk it unless you can return new keyboard for a full refund (component suppliers usually charge for returned goods which aren't faulty).
 
Solution