Answer: When my friend went to the movies, she bought popcorn, and then sat in the front row, and finally, she went out for something to drink.
Explanation: just add comments when you would normally pause, so read it out loud and listen for when you stop talking.
Further: If you can change the sentence I would say: My friend bought popcorn and a drink when she went to the movies, and she sat in the front row.
