Warning: Check to see that you have the appropriate permissions
This layer or table is read-only, or you lack the proper permissions to edit it.
Solution: Check the file properties in Windows Explorer to make sure you have write access to the geodatabase, files that compose the shapefile, or the folder that contains the data you want to edit. This can commonly happen if you have copied data from a DVD or CD-ROM.
If you are using data from an ArcSDE geodatabase, ensure that the data is registered as versioned and you have write access to the version.