The way it is explained in the article seems a bit long winded you can do it quite quickly another way
(not macking the article it is a good one).
1. Open the pictures you want to use.
2. Crop the picture to the size you want using the crop tool on the left panel (try and keep them to the same width if you are going to put them in a straight line downwards).
3.Once you have them how you want them calculate the length and width that you will need in pixels (use the image size menu to help).
4. Click file and choose new from the drop down menu, when the new menu appears type in the height and width sizes you require and click OK.
this should then give you a new blank canvas on your screen ( you can have whatever colour you want I always bring mine up white) make sure you have it at 100%.
5. Using the tools in the left box select Marquee and then mark out the area you want from one of your pictures (this\'ll give you a dotted line around the picture.
6. then select the move tool and drag your picture across to the new canvas and let it go (don\'t panic you still keep the origonal picture) you can then move the picture around inside the new canvas to the position you want.
7. Do this to all the pictures you want to include in the montarge, if you are not happy with the position of one then you can reselct it by using the bottam right panel and selecting that layer. You can also use the layer menu to send a picture to the front or back of the canvas (useful if you want to put in a close up shot of a face).
8. Once you are happy with everything select Layer from the top menu list then choose flatten image (once you have done this you will not be able to make any corrections to individual pictures inside the montarge)
9. After that it is a case of re-sizing if you want to and then saving for the web.
It is a lot easier than it sounds trust me after all I can do it
Edit: aAnybody want me to do an article on it I can but I think it will be a bit overkill seeing as there is one there already but I can put it in a word doc for you if you would like