How can a penis enter into a vagina easily?

Arousal & lube: The owner of the vagina needs to be ready and willing to have sex. Start with foreplay and make sure the woman is very aroused before attempting any penetration. Applying lubricant such as astroglide or pjur can help. If it hurts too much, stop, cuddle and try again later. Eventually, if both of you want it, it will be easy and very pleasant.