You need to paste your structure file in the 'Prepare query HERE' box.

2. Search the Structure database

Click on the red button in the ‘Submit’, and the SMILES will appear in the box.
Click on the button with an arrow. View the search results:
NSC and CAS number in the lower frame window.

Copy the CAS number or the name by using the ‘copy’ function in the ‘edit’ menu of your browser,
and paste it in the query box on the 127,000 3D structures page.