@Amelie43
Hello Amelie and welcome to Airbnb hosting, I hope all your guests turn out to be just as nice as your first has been.
@Sandra856 @Susan869 @Sarah977 have told you that you will be email prompted to write a review once the guest leaves but, just in case you did miss that prompt follow this screenshot.
Log onto your account and you will notice a small green dot next to "Messages" in the option scroll line. Click on that and you will see the guests who you currently have to review.
Click on the guest you are being prompted to review and the review box will appear and walk you through the writing of the review.
Both you and the guest have 14 days from the end of the stay to submit a review, and when Airbnb have received both your reviews they will publish those reviews on each others profiles.
Good luck Amelie. I will look forward to seeing what you write.
Cheers.....Rob