The people miscounted Moshe's return and thought they needed a new god. So they gathered around Aharon and asked him to make them a new god.
Aharon told the men told the men to bring their wives and childrens jewleryt, knowing they may not give it uo to the men, but the men brought their own gold and created the akel . Ahron, told them they will celebratee for Hashem tommmorow.
Hahem told Moshe to go down to the mountain because he was very angry at bnei yisroiel for sinning and wanted to destroy them. When Hashem told Moshe to leave him, MOshe davened for bnei yisrel and reminded Hashem about the prmose to the avos.