10 The LORD said, "What have you done? Listen! Your brother's blood cries out to me from the ground.
11 Now you are under a curse and driven from the ground, which opened its mouth to receive your brother's blood from your hand.
12 When you work the ground, it will no longer yield its crops for you. You will be a restless wanderer on the earth."
13 Cain said to the LORD , "My punishment is more than I can bear.
14 Today you are driving me from the land, and I will be hidden from your presence; I will be a restless wanderer on the earth, and whoever finds me will kill me."
15 But the LORD said to him, "Not so  ; if anyone kills Cain, he will suffer vengeance seven times over." Then the LORD put a mark on Cain so that no one who found him would kill him.
16 So Cain went out from the LORD's presence and lived in the land of Nod,  east of Eden.
Why he is afraid to meet people who may kill him? There were only Adam+Eve+Abel(died)+Cain, why he worried to meet people? Where came the people ?
And, Cain married who?