To edit a resource, you can directly consult the list of resources from the Reservation area. You can search for the resource based on its title. Once you have selected the resource you want to edit, simply click on the edit icon. 

You will find yourself in step 1 of editing your resource.
Your changes will be taken into account each time you click Next. 

If you would like to learn more about the 6 steps of creating a resource, you can read this article.