I'm a Muslim who went to Europe 15 years ago. Unfortunately, I strayed from the right path, and I did Fawahish like Zina, drink alcohol, gambling, and ate pork. I came back a year ago to my Muslim country. I want to do Tawbah, but I don't know how to do it. Do I tell an Imam about what I did so he could punish me, so I can avoid God's Punishment, or do I keep silent?

Praise be to Allah, the Lord of the World; and blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

Hasten to make sincere repentance, return towards Allah, regret the sins you have committed, and be determined not to repeat sins. If you have to pay others' rights then give them back their rights. Everyone who makes repentance Allah will accept it. Do not inform anyone of what you have committed. Cover yourself as long as Allah has covered you. Multiply performing good deeds as much as possible since the good deeds wipe out the bad deeds. Allah Says (interpretation of meaning): {And perform As-Salat (Iqamat-as-Salat), at the two ends of the day and in some hours of the night [i.e. the five compulsory Salat (prayers)]. Verily, the good deeds remove the evil deeds (i.e. small sins). That is a reminder (an advice) for the mindful (those who accept advice).}[11:114]
Do not return to those non-Muslim countries where you face much immorality instead keep living in Muslim countries.
Allah knows best.