If you want to send the project file, they will need Photostory and all the resources used in the project ie images, video audio etc and this would be too much to send by email.
If you want to send the final video, you need to export it from Photostory to a suitable video format eg mp4. However this gives you another problem - depending on your Email provider, and theirs, the email may be limited in the size of attachment allowed - this could be as low as 2MB.
You would be better of using somewhere like Dropbox to upload it to, send the recipient the link and then they can download it.