There are only two requirements you must meet to be eligible for an adjustment of status. You must be a qualifying relative of a US citizen and you must have been lawfully admitted to the US. A qualifying relative is a spouse, parent, or unmarried child under 21. To be lawfully admitted you needed to have entered the US on a visa, like a tourist visa or employment visa, or you came without a visa and were granted specific parole. Even if you have overstayed your visa you can still qualify as long as you have not left the US and reentered unlawfully. If you meet these requirements and have no serious criminal convictions or immigration violations, then you can apply for an adjustment of status and if approved, obtain a green card in a couple of years.