Theme for english B is a poem written by Langston Hughes when he was in college commanded by his proffessor, and we can infer that from the title of the poem, so we know he is in college and he is speaking to Harlem, and to the city about his struggles and dreams, so we know that he lives in Harlem, that is all we can infer from the excerpt, we could discover more from the whole poem, like the fact that he was the only black student at college, but in this excerpt he doesn´t mention anything about it.
We know from the title that he might be in college. (English B is an add way to name a class, but it is the name of the class).
We know nothing about dating a white woman. There is no mention of anything that would tell you that. We are not even certain he is black, not directly anyway.
"Today nobody brought his or her instrument" is correct. It is common for people to use "their" in a sentence like this, but "his or her" is the more proper term.
