2 - Ruth gleans in the field for Naomi. Boaz notices her, has heard of her loyalty to Naomi and to Yahweh, and so is generous to her.
3 - Naomi asks Ruth to initiate a proposal to Boaz, going to him at night during the harvest. He is willing to buy back Naomi's land, and produce an heir for Naomi, marrying Ruth.
4 - Boaz goes right to the city gate and asks the closer kinsman-redeemer if he wants to redeem Naomi's land. He says yes, but then no when he hears Ruth is part of the deal. Boaz redeems her/them, and produces an heir who is an ancestor of David and thus of Jesus.