Load DEM into ArcGIS

I download the DEM (Digital Elevation Model) files from Geocommunity to do the exercise of Archydro model to analysis DEM file for the collection of geographical information. Geocommunity is the free port providing the free GIS files from all over the world. Its format of DEM files is SDTS (Spatial Data Transfer Standard). In order to transfrom the SDTS file into the suitable format for ArcGIS 9.2 use, we should add the new extension by going to ArcCatalog->Tools-> Customize-> Arcview 8x tools.
The transformation of SDTS file to Grid file for the DEM analysis, it follows the steps

1. Open ArcToolbox
2. Under Conversion Tools > Import to Raster, choose 'SDTS Raster to Grid'
3. In the Input Prefix box, navigate to the folder with the ****.ddf files, and choose the 4 digit input file (ex:1158). Note that the path for the .ddf files may not contain any spaces.
4. Choose the Z-value field name for the Record No. box, i.e. "ELEVATION".
5. Select an output folder and name the Grid.
6. Keep Convert Values and Use Data Dictionary checked.
7. Hit OK.
8. You may then add this DEM Grid to ArcInfo Desktop or ArcView 3.x

For more comprehensive information, we can go to the website.