This is my first time with scheduled scripts (I have only really done client side script prior to this), and I am having a difficult time figuring out what API calls I am supposed to be using.

I am also unsure how to go about testing a scheduled script.

To summarize, the script needs to look through all of today's sales orders, check the items in the order, and then check if any of the items have a certain value in a custom field. As soon as it finds an item with this value, it will set a custom boolean field on the sales order to true, save it, and move on to the next one.