Changing canvas color??

[bash]

I have created an image with a transparent background.

When i exported this image into a dark background, the jagged edge around the
images are visible.

How can i change the color of the canvas background so i can see the jagged edges of the images before i export?

I have had to open my image again in Photoshop but cannot find an option to change the canvas color?

Also when i have created an image with several layers. How is it possible to save the image so it is not flattened and i can open the image and amend each of the layers when required?

Sorry for sounding dumb

Can someone help please?

[DDD]

just place a layer at the bottom and use the paint bucket tool to fill it with a color. Or open a new doc. then change the color drop down to bgrd color. It will use the color that is set as the bgrd on the swatches in the tools panel

[bash]

just place a layer at the bottom and use the paint bucket tool to fill it with a color. Or open a new doc. then change the color drop down to bgrd color. It will use the color that is set as the bgrd on the swatches in the tools panelAt last!!!

Thank you very much friend :-)