if you are a worker from a foreign country with h2b visa do you have to file for a tax return?

Yes.

Form 1040NR if you have not been here for at least 183 days.

BOTH Form 1040 and 1040NR is over 183, but less than the full calendar year.

Form 1040 if you have been in the U.S. for all of 2006 (except for vacations).