Loading the 405 is a pretty straightforward affair. You simply place the packet of film into the holder, tucking it back under the bracket near the hinged end of the holder. Be careful to have all of the white pull tabs, and the larger black one, outside the holder when you close and latch the whole thing. The metal bail will come down over the tabs - not to worry. When you pull the black sheet out to get ready for your first shot, the white, number one tab will become evident. Place the holder in the camera, pull the black cover sheet out, remove the dark slide, shoot, pull the white tab and then the film tab to run the film through the rollers. Count out the appropriate time, strip the picture from the backing and voila!
On another note: I just had to make a dark slide for my 405. The black plastic one that came with it was somehow leaking light so that the second and third shots of whatever I was photographing would be fine, but every time I removed the holder from the camera, the following shot would be ruined- totally white. I used aluminum flashing for the dark slide replacement and all is well.