Photoshop help with copying please

Trying to do my first 'proper' repaint useing a kit and Adobe Photoshop. It's the first time i've used PS and I can't believ how HARD it is to use! The help is next to useless don't you think?
Anyway, by trial and error, i've got the jist of it but have hit a wall. I've done the engines and tail fine but the fusalage needs to be split into three sections after you've painted it before it will format properly.
No probs, found how to 'Ctrl+C', etc. the first time and lined them up on the template. All worked but after seeing it on the plane, I wanted to change something. So went back to the original fussalage i'd done, changed the offending item and went to copy it to the template.
Problem is, when I highlight the section I want and press Ctrl+C, it says 'it cannot copy because the selected field is empty'! ARRGGHH! I can see the pic right in front of me, WHAT am I doing wrong?
Any help gratefully recieved, i've been on this for 8 hours and have no hair left to pull out!
Anyway, by trial and error, i've got the jist of it but have hit a wall. I've done the engines and tail fine but the fusalage needs to be split into three sections after you've painted it before it will format properly.
No probs, found how to 'Ctrl+C', etc. the first time and lined them up on the template. All worked but after seeing it on the plane, I wanted to change something. So went back to the original fussalage i'd done, changed the offending item and went to copy it to the template.
Problem is, when I highlight the section I want and press Ctrl+C, it says 'it cannot copy because the selected field is empty'! ARRGGHH! I can see the pic right in front of me, WHAT am I doing wrong?
Any help gratefully recieved, i've been on this for 8 hours and have no hair left to pull out!
