Add another 'solvent' ethanol

As you might have noticed, ADFinput comes with a number of predefined structures. One of these is the 'Solvent' structure Ethanol. Usually, you would not want to replace any hydrogen (or any other atom of the existing ethanol) in order to add a solvent molecule. Fortunately, structures can also be added in empty space:

Select the Structures → Solvents → Ethanol structure
Left-click in empty space near the hydroxyl group

Note that the oxygen is selected and that a potential bond is shown. Again, this oxygen is defined through having xyz-coordinates (0,0,0). Since you are now in 'bonding mode', you can connect the oxygen to any atom.

Left-click on the hydrogen atom of the hydroxyl group

The new structure will be orientated according to the new bond that has been formed. This new bond is, of course, not a real single bond. The molecule builder, however, places no restrictions on the number of bonds on an atom. The new bond is selected, so you may directly delete it if you wish.