The girl's account was given to police and the video recording of the interview was played at Johnson's trial at Bradford Crown Court.
The 28-year-old, sacked by Premier League club Sunderland last week, denies two counts of sexual activity with the girl, who was 15 years old at the time of the alleged incident.
Former Manchester City star Johnson has admitted one count of sexual activity with a child and another of meeting a child following grooming.
The jury watched the girl's police interview during which she described how Johnson was her favourite player.
“I got a message from Sunderland player Adam Johnson, who I'd idolised for quite a while,” she said.
The girl said that, after exchanging messages, she first met up with Johnson on January 17 last year when he signed two Sunderland shirts for her.
She then explained how the player continued to message her, talking about getting a “thank you kiss”.
“I was well up for it. It was a surreal type of thing,” she told the police officer.
“I met up with him again. I gave him his thank you kiss and more,” she said.
Johnson sat in the dock watching the girl give her account on two large video screens in the court.
The girl described how Johnson exchanged WhatsApp messages with her after their first meeting, saying “you owe me for this” and “am I going to get a thank you kiss?”.
The teenager said that at the second meeting, in the player's Range Rover, Johnson said to her: “I've come for my thank you kiss.”
She said that she eventually told him “go on then”, and they began kissing.
“I was kissing him for quite a while,” the girl said.
“He got his hand down my trousers. He started to put his hands in my knickers.”
The girl then described to the officer further sexual activity between the pair.
The girl said Johnson knew how old she was, what school year she was in and where she sat at Sunderland matches.
She said: “He asked me when I was 16.”
Asked how she felt, the girl said: “As much as I expected it to happen, I was a bit shocked it had. I sort of knew I had done something wrong.”
She then said: “It wasn't that I didn't want it or anything. I just knew it was wrong. I'm not one for being able to hold guilt.”
The jury of eight women and four men was played a second police interview during which the teenager described more serious alleged sexual contact between her and Johnson. – AFP
Original source: Teenager testifies in Johnson case