Short answers, pulled from the story.
The Salt March aimed to protest the British Salt Act and declare India's sovereignty through civil disobedience. The movement targeted a tax that represented 8.2% of total revenue collected by the British Raj and hurt the poorest Indians more than any other law.
Mahatma Gandhi began the march on the 12th of March 1930 from Sabarmati Ashram. He and 78 volunteers covered 385 kilometers over 24 days to reach the coastal village of Dandi in Navsari district.
Over sixty thousand people were arrested by the end of April as part of the Salt Satyagraha campaign. Thousands of women emerged from seclusion to join Congress demonstrations and assist in picketing despite police efforts to stop them.
Jawaharlal Nehru led the movement alongside Mahatma Gandhi while the Congress Working Committee gave Gandhi responsibility for organizing the first act of civil disobedience. They chose the 1882 Salt Act as the target because it affected every class of citizen.
Sarojini Naidu took command of the remaining protesters after Gandhi was arrested near Poona on the midnight between the 4th and the 5th of May 1930. Soldiers clubbed unarmed satyagrahis with steel-tipped lathis, causing severe injuries and death among the marchers.
The movement ended as official policy in 1934 when Congress leaders decided to stop satyagraha. The British did not make immediate major concessions despite the pressure and over 60,000 Indians had been jailed as a result of the campaign.