Sims 4 CD and extension CD?

I recently got the sims 4 CD gift. I also like extensions like "dogs and cats", "big city life", "…"…

Now the question: How can I use the erweirerungen if I already have a CD in the laptop in it?

You install the extensions via CD or online code on your laptop and then you can easily access them by going to the main game. The extension is almost only new content that is brought into the main game

Many Thanks