1. Open an existing solution (Start -> All Programs -> Microsoft Visual Studio -> File -> Open -> Project/Solution). If you don’t have an existing solution, then you can create a new one by following the directions here.
  2. Within the “Solution Explorer” section, right click the project (the node under the “Solution”) and select Add -> SharePoint “Images” Mapped Folder.
  3. Within the “Solution Explorer” section, expand the “Images” folder.
  4. Right click on the folder inside the “Images” folder and select Add -> Existing Item.
  5. Browse to the image file that you would like to use then click “Add”.
  6. Within the “Solution Explorer” section, expand the “Features” folder and double click the feature that you would like to add an Feature Gallery icon.
  7. Within the “Properties” section, enter the following into the “Image Url” attribute: the name of your project followed by the “/” character followed by the file name of the image you selected in step 5.
  8. Build -> Build Solution.
  9. Deploy -> Deploy Solution. Finished!