If you came to this country through marriage to a US Citizen and you were married for less than two years at the time, then you are a lawful permanent resident who will need to remove the conditions on your green card within the 90-day period of your two year anniversary of becoming a permanent resident. You will have to file form I-751 in that 90 day time frame, and supplement that application with evidence that you have continued to have a bona fide relationship during the two years.

Here is some criteria to keep in mind:

Eligibility – You are eligible to remove your conditions if

After two years you are still married to the same U.S. Citizen or permanent resident. And you can include your children in the application with you, or
You have a valid reason for not being included in your parent’s application and you are a child, or
You entered your marriage in good faith and you are a widow or widower, or
You entered your marriage in good faith but it ended through divorce or annulment, or
You entered your marriage in good faith, but you or your children were battered or subject to extreme cruelty by your US citizen or permanent resident spouse, or
You would suffer from extreme hardship if you were deported from the US.

Initial evidence to provide:

Copies of your permanent resident card and that of your children that you have included in your petition.
Copies of documents that support the petition and provide evidence that the marriage that you were granted conditional status for was entered into in good faith and not to evade immigration laws.

Examples of this type of evidence include:

Financial records that show joint ownership of assets or that you both are jointly responsible for liabilities (ex. Checking accounts, joint tax returns, utility bills etc).
Lease or mortgage documents showing both of your names.
Birth certificates of children born during the marriage
Affidavits by people who have personal knowledge of your marriage and relationship together
Any other documents that you think are relevant

You can submit as many documents as you like, and you should submit a good amount with your petition. You will most likely be scheduled for an interview where they will question you and your spouse similar to how they did when you were applying for permanent residence.

If your relationship has ended, you should still submit evidence establishing the relationship was bona fide at one period in time and then document the relationship from that time until its demise making sure to describe things related to how it ended with outside evidence, if possible.