Here is the before pic (sorry, didn't want to include it and give away who was added in!)
Thank you for all your comments. I took this photo at my friend's mother's 60th, and ended up adding the "young couple" in the back (thanks for that especially - that's my hubby and I!) because we were taking pics and never got in one! I just wasn't sure if I should include it in the disc I'm giving them with pics on it because I thought it was quite obvious. But I think I'll include it after all!
Oh...how I did it. Well I'm not sure on all the technical terms with photoshop - I know how to do a lot with it but only from experimenting. I took a pic of hubby and I from the party and traced around us and cut us out. Then I took the section of the group shot that I wanted to add us to, and I made a duplicate layer of that area (so I could make it look like we were behind the people in that area, if that makes sense). I then copy/pasted us into the shot, placed us where I wanted us to be, then used the eraser tool to get rid of all the extra areas around us (sorry - told you I didn't know all the technical terms!). Then I used the smudge tool around the people around us where you could see the sharp lines from the eraser. It just took time and patience, and doing little bits at a time so I could undo it if it didn't look right and didn't have to start all over again.