Step 1
Follow the instructions in the documentation found in the distribution file.
(All original distribution files contains a documentation file telling you how to use the action)

If you used the FilmStrip [Perspective] action you should have an image looking something like this:

Step 2
Crop the image to using the Crop Tool (Ctrl + c). It is not necessary to crop the image, but you really don't need all the "space" around the negative. Here's my cropped image:

If you flatten the "FilmStrip image" the background on that picture would be white, and it would look good only on a web page that has a white background.

Step 3
Resize your image to the size that it is going to have on your web page. If you add a background image to your picture before you scale it. The background will differ from the original background image.

Step 4
Ok, let's say that you have a web page with this background image:

Open this image in Photoshop and choose Select > All  (Ctrl + A). Now choose Edit > Define Pattern. Close the image.

Step 5
Go back to the "FilmStrip image" and make sure that the Background Layer is active in the layers palette:

Choose Edit > Fill and choose to fill using Pattern. Flatten the image by choosing Layer > Flatten Image.

PS!
In order to work with the background layer in Photoshop 7.0+ you have to double click on the layer and give it a new name (or simply clik OK in the dialog box that appears)

Here is the finished image: