the direct object of diri.
Mi diris saluton (I said hello)
Mi diris vin (I told you)
You do seem a little confused about basic English grammar, I must say!
The second, if followed by a written stop, is NOT correct in Esperanto, unless it is punctuated thus: 'Mi diris "vin"'. - Here 'you' is an indirect object in both English and Esperanto. It should be: Mi diris al vi, ke ....
I told you what? The unexpressed 'what' is the direct object, 'you' is the person TO whom you are telling it/what.
In English the 'him' in"
1) I see him
and 2) I give him the book
might look the same, but the first is a direct (accusative) object, the second is an indirect (dative) object. Students of Latin, German, Russian, Greek, Irish, Polish, Serbo-Croatian and other case languages, need to learn this fast - otherwise they are forever lost.
1) = Mi vidas lin.
2) = Mi donas al li la libron.
Buy yourself an ice-bag to cool the brain while reading, then check this good summary out: http://en.wikipedia.org/wiki/Object_(grammar)
Hope that this clears this up once and for all for you! Good luck!