You must first repent to Allah for leaving an obligatory fast without a valid reason, as this is a major sin. Then you have to make up the missed days. But if you had intercourse while breaking a day of Ramadan, this is a different story.

Read more

This is a sunnah. Kindly refer to the following link(s): https://m.youtube.com/watch?v=lGUfHl8HRK8

Read more