Create a table that has columns:
ID - Int, Identity is fine, this serves as a unique row identifier
UserID which links to the User table and identifies the user answering the question. (Foreign key)
QuestionID which links to the table of questions to identify which question the user is answering (Foreign key)
Answer given - depends on rest of your system what this is.
Titmestamp - DateTime. This is optional, but I'd include it because I'm like that...
Probably, you have a Quiz table which the Questions table refers back to.
Then, when he answers a question you create a new row in the table which refers to the user, the question, and his answer (and timestamps it so you know when he answered).