help! null/alternative hypothesis?

QUESTION: If we are interested in testing whether the mean of population 1 is smaller than the mean of population 2

how would you state the null hypothesis? and the alternative hypothesis? from the above information

would the null be u1-u2 < 0 ??? i'm confused......

H0 usually contains an equal sign. In your case you want to test if u1-u2 < 0 so it's the Ha, and the H0 would be u1-u2 >= 0.