I am a US CITIZEN and in the middle of process for a green card application for my dad. However, I have been unemployed for the past 2 years.

In your case, you need a credible joint sponsor of sizable income and/or assets unless your father is of working age and has a history of good employment. In the latter case, the person doing joint support does not require such a  a large amount of income/assets. You can either put down $0 if you made no money in 2018, or an estimate of your current income with proof of the amount. Your father will basically be relying on the joint sponsor for the financial support. It should be a close friend or relative, and it might help to have your joint sponsor give a statement that he or she recognizes the obligations of support and the reasons for which he or she would assume the obligation. Due to the limitations of the Lawyers.com Forums, Alan Lee, Esq.'s (the "Firm") participation in responding to questions posted herein does not constitute legal advice, nor legal representation of the person or entity posting a question. No Attorney/Client relationship is or shall be construed to be created hereby. The information provided herein by the Firm is general, and requires that the poster obtain specific legal advice from an attorney. The poster shall not rely upon the information provided herein as legal advice nor as the basis for making any decisions of legal consequence.