I did some tutorial jobs in last summer and earned quite a few thousand dollars. Of course, most of the income came as cash or personal checks and I will not get something like w2. Could anyone over there advise me how to file tax federal/state tax returns in such a situation? Huge thanks in advance.

You are required to report all your income.
This income is yourself employed income. You will report your income and business related expenses on schedule C or C-EZ (Form 1040). Then you put net income (or loss) on line 12 of Form 1040. This income is subject to SE tax at 13.3% (this is shown on line 57 of Form 1040). Your U.S. Tax Return: Tax Filing by Self Employed Sole Proprietor or Independent Contractor

Hi, MukatA,

Thank you very much for your clear answers to my question. I wonder if I need to provide evident for how much I earned and for how much I spent to earn the money. I guess, travel tickets and rental receipts are useful. The problem is that I have not kept all these for tax return as I did not know that they are useful until I read your answer. Any suggestion on what I can do on this?
Huge thanks!