You can make a raffle but you need to make it provably fair, you can't ask a moderator for a number because he will give you the number of his raffle...
What do you mean provably fair?
You did not realize how it works. When you buy a raffle you have to deposit the amount in my account and this corresponds to a transaction in my bitcoin wallet and this is your raffle so when I say that I will ask a number to a moderator he will never know the position of his Transaction in my wallet.
Provably fair means that no one else will know the possible result (the number) . If you will use a random number generator Like random.org, that is provably fair. I don't think a moderator is what you will need for a raffle like this also. You need an escrow that will hold the prize money and the raffle entry money. it also doesn't look like people will be interested in a raffle like this that are being hosted by a newbie.