Things to Remember
Step 1: Download both CM file and Gapps files to your Computer.
Step 2: Now, connect your device to your computer with the help of a USB cable and copy the downloaded ROM and Gapps files into the root directory of your device’s internal/external memory.
Step 3: Switch off your device completely.
Step 4: Boot it into “CWM Recovery Mode”. To do so, Press and hold “Volume down + Home + Power Key” together for a few seconds.
Step 5: In the CWM Recovery menu, perform the “Wipe Data / Reset” and “Wipe Cache Partition” tasks to delete the existing data.
Step 6: Go to advanced and perform “Wipe Dalvik Cache”
Step 7: Go back and from the CWM Recovery main menu, choose “install zip from SD card” option -> select the ROM file -> tap “Yes”; now the installation process will start.
Step 8: The installation process might take some time, so please wait for the completion.
Step 9: Once the ROM installation is completed, you have to follow from “Step 7” again and this time you have to choose “Gapps” file instead of ROM file.
Step 10: Once the all the processes are completed successfully, do “reboot your device” from the CWM Recovery main menu.