Edit and Change the Background of an Image

You can share the image here if you get stuck, and I am sure someone will get you started.  

Can you post a screenshot of what the image looks like? And what the background looks like? is it a JPEG?

If it's a flattened file (only one layer and that layer is a locked Background layer), unlock it by clicking on the lock icon in the Layers panel (Window > Layers). At the bottom of the Properties panel (Window > Properties) in the Quick Actions section, select Remove Background. Then you can add whatever background you like in a layer below that layer.

Similarly, you could use the Object Selection tool (if you can't find it, use Ctrl on Windows or Command on macOS + F to search for it by name) to select the content you want to keep. Shift + select if there are multiple parts to keep. Then invert the selection by going to Select > Inverse. Use Generative Fill (Edit > Generative Fill) to use AI to create content to fill in the selected area based on the text you enter or leave it blank and have it fill it in for you based on the image.