I suppose it's a bit late to advise you on writing your e-memo for your
class, but for anybody else who stumbles upon this, I'd like to give my
2 cents...
A typical memo as I know it should contain the following information:
To whom it is addressed,
from whom it is being sent,
the date it is being sent,
the subject of the memo and
the text of the memo.
If you're writing an e-mail, you don't have to worry much, just write
it as a regular e-mail but don't forget to enter the subject in the
defined space since, if I'm not mistaken, some e-mail clients might
allow you to send an e-mail without a subject, but you don't need to
write the subject in the body of the e-mail.
And as JoAnn pointed out, even though memo can be written in a bit
relaxed tone, you should still watch your language.
I guess the most important thing to be aware when writing memos is that
they're written in an informal language, direct style and no greetings
nor closing is necessary.
Best wishes,
Dom Delimar
http://business-letters-101.com