It is very easy to block a or more websites in tenda router.
Visit to Tenda Router using ip: http://192.168.0.1/index.html
Now, Login in Tenda Router.
In default will auto connect (no need to login)
But, If password wants then use: admin
After login, Click on “Parental Control” from Right Menu
Now, “Turn on” A device on which you want to block.
Allow Access At: Make all: 00 00 00 00
Website Restrictions: Allow
Websites Specified: Type: website url and Click on “Add”
Finally Click on “Ok” Button