Step 1: Prepare the HCN molecule

Start ADFinput 
Draw an HCN molecule
Select the C-N bond and make it a triple-bond
Pre-optimize the geometry

You should get a linear molecule as shown in Fig 1.

Select the "Geometry Optimization" preset
Select the DZP basis set
Save the molecule with the name HCN_GO
Select 'Run' command from the 'File' menu

The geometry will be optimized, using a DZP basis set.

Click "Yes" when asked to read new coordinates from the HCN_GO.t21 file
Check the C-N and C-H distances

They should be about 115 and 108 pm (1.15 and 1.08 Angstrom), respectively.

Write down the value of the bonding energy printed at the end of the calculation
  in the ADFtail window