When I am installing the caynogenmod 12.1 on recovery 3e the verifying signature is failing. What happened in this my device. Thank you so much.
"3e" is the stock recovery, which doesn't support flashing custom ROMs. It will only accept packages signed by the manufacturer. So if you want to flash a custom ROM, you'll have to install a custom recovery first.
For details, see our recovery-mode tag-wiki. For example candidates, also see clockworkmod and twrp. Moreover, the place where you downloaded your ROM image will have given you the necessary details. If not, head over to the CyanogenMod Wiki on your device. Once you've identified your device, check the Download page for the image. Instructions can be found from the Devices page.