How do I use ArcGIS to select data for a particular country from an African dataset and to convert it to .asc format?
I am sure people would love to help but:
May I presume that the .asc format you refer to is the ASCII Raster format? What does the African dataset look like? If this is raster data, you can use the Clip (Data Management) tool and using the country as Clipping Geometry. Next convert to ASCII format using the Raster to ASCII (Conversion) tool.
In case you have vector data, clip the vector data first, convert to raster and then convert to ASCII.
Retrieving data ...