I left out a few words I'd like you to check. I think sentences 4-5-6 are too confused. Would you please help me check them? Thank you.

1) Can I have an aisle/window seat?
Can I have a seat in the front (of the aircraft)?
2) We'll have to make a stopover/layover in Madrid.(What does this sentence mean?)
3) Attach a luggage label to your luggage in case it gets lost.
4) Last Saturday the dark-skinned girl in the picture was at Jessie's party.She says that Jessica had made a lot of food and had invited all her classmates.
5) Jessy's friend confesses that she has always fancied Ian. He started chatting her up at the party but then a girl turned up and they had a row.
6) Jessy's friend realized the two of them were going out together. When Ian came over to her, she ignored him and walked away.

Which book/what kind of books would you take with you to read on a desert island?
Magazines about fashion, music, sport, beauty, health: fashion/music/sports/beauty/health magazines
Which sport(se) do you practise?
To organize a end-of-exams party

1) OK

2) We'll have to make a stopover/layover in Madrid.(What does this sentence mean?) This means that you won't go straight through to your destination. The train or plane will stop (in this case, in Madrid) where you may or may not have to go to a different plane or train to finish the journey.

3) OK

4) OK, as long as you put a space after that period.

5) Jessie's friend confesses that she has always fancied Ian. He started chatting her up at the party, but then a girl turned up, and they had a row.

6) Jessie's friend realized the two of them were going out together. When Ian came over to her, she ignored him and walked away.

Which sport(s) do you play?

To organize an end-of-exams party

4) Last Saturday, the dark-skinned girl in the picture was at Jessie's party. She mentioned that Jessica had prepared a lot of food and had invited all her classmates.

Explanation: Sentence 4 seems fine grammatically. It describes the situation of a dark-skinned girl in a picture being present at Jessie's party. The girl states that Jessica had made a lot of food and had invited all her classmates.

5) Jessy's friend confesses that she has always fancied Ian. He started chatting her up at the party, but then another girl showed up, and they had an argument.
Explanation: Sentence 5 is a bit confusing due to the use of pronouns without clear antecedents. A possible revision could be: Jessy's friend admits that she has always had a crush on Ian. He started talking to her at the party, but then another girl arrived, and they got into an argument.

6) Jessy's friend realized that the two of them were dating. When Ian approached her, she ignored him and walked away.
Explanation: Sentence 6 seems clear grammatically. It describes how Jessy's friend came to the realization that Ian and someone else were dating. When Ian approached her, she ignored him and walked away.

Overall, the revised sentences should provide clearer explanations of the given situations.