In Captain America:Civil War, the Avengers split over
the signing of the Sokovia accords
which makes The Avengers split into 2 teams both lead by Captain America and Iron Man
Team Captain America
Falcon,Winter Solider,Ant-Man,Scarlet Witch,Hawkeye
Team Iron Man
War Machine, *Black Widow, Vision, Black Panther, Spider-Man
The two factions of the team have a fight over
Steve helping the Winter Soldier, leading to several of the anti-registration faction being taken into custody.
Later, as the MCU wiki says.
Stark finds evidence that Bucky was framed by Zemo, and finds that the rest of Rogers' team have been thrown into prison. Heading there, Stark then knocked out the audio feed and revealed to Wilson that he was trying to help Steve Rogers and learns where Rogers and Bucky are going. He then follows the two to Siberia, and is shadowed by T'Challa. Rogers and Stark reconcile, and as they explore the facility, they discover that the other Winter Soldiers have been murdered by Zemo who had never intended to release them.
Zemo reveals that he is a Sokovian and wants to punish the Avengers for the death of his family during Ultron's attack. Zemo shows Stark a security video from 1991, which reveals Bucky as the assassin who murdered Stark's parents to steal samples of the Super Soldier Serum from their car. Rogers admits that he knew the circumstances of their deaths, and although he didn't know Bucky was behind it he is still siding with his friend. A disillusioned and enraged Stark turns on Bucky, forcing Rogers to fight him to save his friend's life. Bucky loses his robotic arm in the fight, but Rogers disables Stark's armor and departs with Bucky, leaving behind his shield, accepting that he no longer deserves it.
Stark receives a package containing a phone and a letter from Rogers. In the letter, Rogers apologizes for everything that happened and for not telling him the truth about his parents, as well as noting his regret that he cannot accept the accords. He gives control of the remaining Avengers to Stark, telling him that he knows the day will come when the team will need to come together and act as one. When that day arrives, Rogers and the others (whom Steve releases from prison) will be just a phone call away. By the time Steve's imprisoned Avengers team are escaped from the Raft by Steve, and Ross calls Stark to get some help from preventing Steve's Avengers from escaping, Tony turned off Ross' call to cover his activities by pretending to be busy on something else, letting Steve and his Avengers team escape successfully.
so i keep thinking In Civil War why were Tony and Steve both enemies and when did they become friends again ? why were they enemies in the first place and did the letter from cap confirmed that their both cool again and are friends again?