The point of a recommendation letter is to offer information that goes beyond what can be determined from the candidate's other application materials (transcript, CV, etc.)
It is therefore in your best interest to choose letter writers who know you sufficiently well. If that's not me, please take a few minutes to reconsider your choices.
If you still want to ask me, please gather all the information that I might need (with links if you have them) and send it to me in one email. This should include:
- what exactly are you applying for?
- are there specific requirements for the letter (in terms of contents or presentation)?
- what is the deadline?
- a draft of your application materials.
Writing a recommendation letter takes time. Try to give me as much advance notice as you can (at least a couple of weeks, if possible).