What version of PhotoSmash are you using? I'm using 0.7.00
In that version I need to 1st create a gallery for the images to go into. Under "Gallery Settings" I created one called "Unattached" activated and saved it.
Then I went to the Admin sidebar under PhotoSmash and choose... "Import Photos". From the"Fetch from" dropdown box I choose the second option <Unattached Images (no posts)>, and clicked "Fetch Images"
The unattached images will appear. I selected my images by clicking on them, which should add a highlighted frame around them. Next, I choose the gallery I wanted to add them to under the "<Select Destination Gallery>". Then clicked the add images button and had a new gallery with just the unattached images I wanted.
HTH,
Rashell