1.For Rooting ur Canvas Nitro .....the best and easy method i reccomend is to use kingroot apk which u can download from attachments below....
2.To Update your Recovery Mode u need to follow these Steps .......
a. Root your device by kingroot ( download from attachment below)
b. Download MobileUncle Mtk Tools (from attachments below) and install it
c. Download TWRP Image file from the attachments below and place it into root directory of ur device
d. Now open MobileUncle MTK tools app and click on Recovery Update
e. Now it will show u the TWRP img file placed in root of ur device.......
h. then it will ask to flash recovery ......click ok
i. then it will ask u to reboot into recovery