can I upload a contract I already have

Do you mean you want to create a Contract Form? If you have an existing form in JotForm similar to the Contract Form you want to do, you can just clone the form and edit the cloned form as needed. Here is a guide on how to clone existing form: How to Clone an Existing Form from a URL. However, if you have a PDF or document file of the form, unfortunately, we do not have a feature where we can convert a PDF or document form to JotForm. You will have to create the form manually.

Do let us know if you need further assistance.
Regards.