I got to the USA through visa lottery and I will like to know when and how can I file for my fiance and the requirement needed?

You cannot file for a fiance as a permanent resident. You can get married and file for him as your spouse and the process will take about 3 years.

You may not file a fiance visa as a permanent resident, and will need to be a US citizen.

LPR cannot file a petition for fiance. Only US citizen can. If you marry, you can file I-130 visa petition for your spouse. It will take about 2-3 years.

You must be a US citizen to file a fiance petition. You will need to wait 5 years after you obtained LPR status before applying for US citizenship.

You will need to seek citizenship by naturalization before you are considered eligible to seek a K-1 Fiance visa. That family-based option is not available to Lawful Permanent Residents (LPR's) under the current Regulations until you become a US citizen. If possible, an alternative would be for him/her to seek an independent avenue (employment-based dual intent classification) for obtaining a non-immigrant visa (NIV), come to the US, marry you, immediately file for F2A classification as the spouse of an LPR (thereby obtaining a priority date for immigrant visa availability) and wait under the existing NIV visa status until adjustment of status can be filed The current backlog for F2A spouses (as per the January Visa Bulletin) reflects that immigrant visas are available in that classification to those holding priority dates of 22 September 2010, a wait of at least 2 years under the current Regulations. You should consult an experienced immigration attorney to guide you in these matters.