Gauri use this to see if they are already installed
ls /usr/src/ | grep 4.3
It may show linux-headers-4.3.0-rc4 as a result and if it doesn't go to the page you downloaded the linux-image from and download the file that begins with linux-headers-VERSION-generic all.deb and the one linux-headers-VERSION-generic ???.deb You want amd 64.deb for a 64 bit install or the i386 for a 32 bit install
Install the two header files the same way you did the linux-image file if the headers don't already exist
Gauri use this to see if they are already installed
ls /usr/src/ | grep 4.3
It may show linux-headers- 4.3.0-rc4 as a result and if it doesn't go to the page you downloaded the linux-image from and download the file that begins with linux-headers- VERSION- generic all.deb and the one linux-headers- VERSION- generic ???.deb You want amd 64.deb for a 64 bit install or the i386 for a 32 bit install
Install the two header files the same way you did the linux-image file if the headers don't already exist