Removing imperfections from a photo is really easy. First open the photo you want to retouch. I am using the photo below:
Click on the Spot Healing tool to activate it:
Select a brush size in the options menu at the top of the document window. The following image is the default settings.
You want the brush to be roughly the same size as the blemish itself. Play with the healing brush options at the top of the document window. Mouse over to the document and position the brush cursor over the blemish. Click one time to make the spot vanish. My finished photo is shown below.