List this remote, where can I purchase new one. My Apple TV is 1st generation

1st generation as in Apple TV 4K (1st generation) (2017)?

Get the (new) Siri Remote for Apple TV (4th generation or later) (model 2015 or later).

The black Siri Remote is no longer sold through Apple, but other resellers may still have a few.

Get the (old style) Apple Remote (aluminum) for Apple TV (3rd generation or earlier) (model 2013 or earlier).

Replacement remotes will have to be paired or linked to the Apple TV box: If your Apple TV remote isn't working - Apple Support