Thank you for your valuable information. that kingroot something. will I just download it at my phone then open and let it do the miracle?. after rooting what would be the best steps or apps to do/download?
Well, I'm used to NOT suggest you to install a Custom ROM if you're not experienced enough. Also, you have got very good chances the official rom of your device should be good enough to grant long life to your device, especially if your device isn't popular enough to attract expert custom-roms developers.
Anyway if you really want to install a custom rom to your device, maybe the following link could help you:
Please note, it's the most stable ROM I found for your Android device but please note there are few bugs.
I'd rather suggest you to customize your official rom, changing its appearence. There are lots of apps on Google Play to customize it.
This way it'll be 100% safe and hopefully without any bugs!