CS5 help?

[ericdinosaur]

I have a series of photos I would like to put in the same photo, like cannonball! | Flickr - Photo Sharing!
But of a friend doing a whip on a downhill bike. There are 4 images through the movement, and I really want to put them on the same image. I've been trying on photoshop for a while now, and just can't seem to crack it. They come out dull and very transparent, with only one 'him' being clear. Can someone shed some light on how to do this please?

 

[tirediron]

This is easily done using layer masks (Google "Layer masks CS5" and "Layer masks CS5 youtube" there are LOTS of on-line tutorials, BUT it's only going to look right if each image was taken from the exact same place (ie tripod).

 

[dexterlitonjua]

ditto

 

[Samerr9]

Choose one photo to include the background you want. Then drag the other 3 into that photo you will notice that each new one came in a layer. For each layer erase everything except the bike in montion. Masking is a nice way of doing that..

Best regards,