Esri provides several point symbols in the ArcGIS Explorer Symbol Gallery; however, you may not find the symbol you need. You can incorporate other point symbols into your map and store them in the Symbol Gallery for re-use. Symbols must be in one of these image formats: .bmp, .ico, .png, .jpg or .jpeg, .gif, .exif, .tif or .tiff. Note that transparency can be set in some of these formats if your symbol requires it.
To add a new point symbol
The Symbol Gallery displays the list of symbols available for GIS point features. You can scroll through the symbols or drop the gallery down to see more symbols. When you click a symbol, that symbol is assigned and the map updates to display it.
Click the Browse… or Add from a Url... button to specify a local file name or Url to use as the source of the point symbol. Symbols specified in this way will be added to a group named My Symbols and remain a part of your Symbol Gallery.
To remove point symbols you've added
You may no longer wish to keep the symbols you've added. They can be removed using the Manage My Symbols dialog, which can be accessed by clicking on Manage My Symbols... at the bottom of the Symbol Gallery.