Shading point shapefile in ArcMap

You can either symbolize your point data with a preexisting symbol that looks like what you want using the Symbol Selector dialog box. You also have the option to modify an existing symbol and save your new version for future use within the Symbol Selector or Style Manager.

Or if none of the existing symbols look like what you want you can make your own symbol in some outside graphics program (Paint, Adobe Illustrator, etc.), save it as a picture file (png, jpg, gif, bmp, emf) and then import it into ArcGIS to use as a picture symbol. In the Style Manager create a new Marker Symbol, in the Symbol Property Editor change the type to Picture Marker Symbol, and click the picture to import the image. Full details in this Esri Technical document.