If i am sending a letter in the usa, and i'm sending it from nebraska to wisconsin, how many stamps do i need to put on the letter?

Well first it depends on the ounce of the letter. If it is a standard one, like a few pages, or a simple card, there is the forever stamps you can get (current price is $0.49), and you can use just one of them, or a first class stamp they have as well. Stamps go in the top right hand corner of the letter. First class letter stamps allow a little more ounces vs the forever stamp.

Overall, just 1 stamp if it is standard sizing. Remember, postal service will return letters due to not enough stamps (payment) or there will be a mini bill left in the person's mailbox to pay the extra postage.