Where to enter the "steam" key?

[Fortuona]

I bought the game but I can't figure out where to enter the steam key. Can someone help me oh beloved community?

 

[Bernfred]

bottom left on steam: Add game... Activate a product on Steam...

 

[Fortuona]

bottom left on steam: Add game... Activate a product on Steam...

Thank you. I got in the game and I must say that it looks better than I expected. Can't wait to get more into it. It is almost 3:00am here in the USA so I am calling it a night but very much look foreword to this game. Thanks again Bernfred!