How to a create a bill for a contractor who is billing by the hour?
This is just the place to get the answers you're looking for, @usermelissa.
To clarify, do you need to bill and enter hours that your contractor works for you? At this time, you can only create a bill, select the appropriate expense account and enter the total amount you owe your contractor.
Meanwhile, you can utilize an integrated third-party app in QuickBooks Online. QBO does offer the support of thousands of various third-party applications for any functionality you may need. To look for an app that can help you accomplish this, head to the Intuit App center and type a keyword in the search-bar.