Здравствуйте. Можете пожалуйста проверить на грамотность. The picture shows a picnic. In the foreground we can see a tray of chips, lemonade and two teenagers. I think they are preparing barbecue. I think that they are in the park. In the background I can see people. They sitting and talking.I think that people in the picture have a good time.

The best variant of the 1st sentence is: We can see a picnic in the pic.
3. they are making barbecue
4. in a park (if u dont mean a certain one)
6. They are sitting