Make the changes you need to make to your PO. If you need to select a different/new vendor, go ahead and do so. If you need to make changes to the line items, you can do so by clicking into the cells in the Items tab of your PO and typing in your changes.

Once your changes have been made, use the Options Menu at the top of the PO to select "Resend Order". It will look like this:

A pop-up box will now appear where you will be prompted to select a reason for resending the order. You will also be given the opportunity to type in the body of the email anything that you want to indicate to your vendor with this resend, and you can even edit the subject line!

When you are ready, click the "Resend" button on this pop-up page and your order has now been resent with the changes you have made!