How do I do it?

A quick check of the game shows that the version we have here is Windows only:

https://www.gog.com/game/tomb_raider_123

Skimming the Tomb Raider subforum, I see this post that offers some advice:

https://www.gog.com/forum/tomb_raider_series/help_i_want_to_play_tr_1_on_my_macbook

At least for the macbook.

Hope this helps