Once you arrive on the viewer page, click on "load folders".
Then select the folder where the DICOM files are located, it is usually called "IMAGES".

Once the folder is loaded, click on the MPR button in the top toolbar.

Then double-click on the desired view to display it in full screen.

At the top, there's a bar with various tools: measuring, zooming, preset selection (usually "bone"), etc.
On the side, there's the scroll bar to navigate through the scan.