After you have a surface created you want to apply the image, click View> Appearance gallery>Edit model appearances>map>color texture>select 'image' then click on the square directly to the left of drop down list. This is where you choose the image you want to use. After you pick an image close the editor. Click to select the surface you want to apply your image. Click the appearance gallery and click the texture located under 'model' if not already selected and then select the surface to paint the image and hit OK or middle mouse button to complete.
