Prepare!
- Did you search online? If you did, what all resources did you refer to? Mention those when you ask the doubt.
- If you did search, but were unable to follow what was described - what went wrong? Mention what went wrong or something you were unable to follow
- Did you check with your peers? Is it a problem everyone is facing? Or is it only you?
If you have done the above, feel fully confident to ask your doubt! And give all relevant information - all the links you tried to refer to and what exactly you are unable to do or follow.
You can simply ask him or her in your assigned task group (avoid messaging in person because other people might have the same doubt) but please do make sure you have done the above before asking.