creating a shadow in photoshop

[flalaw]

thanks to abstract's help i was able to get a really pretty beach picture, on top of which i pasted a picture of me and my girlfriend. i did some photoshopping and resizing and it looks like we're actually there on the beach.

well, here's the next challenge i'm facing. i'd like to put a shadow in, but i have nooo idea which direction to cast it in order to make it look realisitic. i can't really tell where the sun is, so does it matter which direction i cast the shadow? i've attached the picture i'm working with, using stick figures instead of the actual superimposed picture of me and my girl.

also, i'm not sure how to cast the shadow in PS to begin with. i'm looking at this tutorial:

http://www.photospin.com/press/?page=archives&name=Creating%20a%20Cast%20Shadow%20with%20Photoshop

does it look okay to use this technique for a layer that has been cut and pasted into the beach picture?

thanks so much for any feedback!

[CanadaRAM]

Lookit the clouds to help locate a plausible sun position.

The tutorial is about how I would do it. Exploit layers so you can mess with opacity etc.

PS> If you make up postcards of this, the GF is really gonna be p!$$=# that you didn't actually take her to a beach holiday... cheap #$*&(er that you are! :)