How do i add the normal tv channels to the tv like itv blaze and other channels

It depends on "normal" I guess.  For streaming channels, you look in the Roku channel store. Some channels may have their own apps, and some may only be available in packages such as SlingTV, Fubo, YouTube TV etc.

If the device in question happens to be a TV, then you can also connect an antenna to receive over-the-air channels.