An image with a transparent background might be placed against a website background. This gives a Web designer flexibility in placing the image on the page, and it can help make the file size smaller versus creating a large background file with the image included. Not all image file formats support transparency, so the two file types to use are GIF or PNG. Most image-editing software that supports layers can create an image with a transparent section.
Create an image with a transparent background. Look for the setting in the New File dialog box that specifies the background color. Choose "transparent background" from the list, or check the box next to that option.
Open the image you want to add to the transparent image. This is probably an image with a background you want to get rid of, or an image that has a section you want to make transparent.
Copy the image by selecting "Copy" from the "Edit" menu. Go back to the image created in the first step and select "Paste as New Layer" from the "Edit" menu.
Use the "Magic Wand" or "Lasso" tool--it may also be called the "Selection" tool--to select the area you want to be transparent. Select "Delete" or "Clear" from the "Edit" menu to erase the area selected, making sure the layer you created in the previous step is the active layer.
Erase any stray bits you may have missed using the "Eraser" tool, making sure the image layer is still selected.
Check to make sure you can see the "background" through the part you erased. Most image-editing programs display a gray and white checkerboard to signify a transparent background, so you should be able to see this through the part of the image you erased.
Save the file as a GIF or PNG file. Make sure to specify the option to keep areas of transparency.