There are a few different ways that you can go about creating a web banner in Photoshop. One way is to create a new document and then use the Rectangle Tool to draw a rectangle that is the size of your banner. Once you have created the rectangle, you can then use the Type Tool to add text to your banner. Another way to create a web banner in Photoshop is to use one of the many templates that are available online.
You can find these templates by searching for “web banner templates” in your favorite search engine. Once you have found a template that you like, you can download it and then open it up in Photoshop. From there, you can edit the template to fit your needs.