I'm a bit confused on what you are meaning to do. If you mean like a roof of a house the cleanest solution would be to just bend your sheet of metal to the shape that you need it to be.
It would definitely look better if you didn't have to join them at the peak. I would never used screws to attach sheet-metal together, pop rivets work much better and handheld rivet guns are pretty cheap.
You could make a short bend on one side of your sheet metal roof with an inch overhang or so then lay the other side of the flat on it without any bends and rivet them together. This would provide a a relatively clean look and be pretty easy to do. Riveting is pretty easy, you begin by marking your spots and drilling through both sheets that you want to attach with the correct sized drill-bit based on your rivet size. I like to drill through both pieces as the same time if possible in the exact way I want them together. Then you put the thick end of the rivet into your hole with the long shaft sticking up. Then you slide the shaft into the head if your rivet gun, give it a squeeze and you will hear the signature "pop" sound and then you are done.
When working with sheet metal its always good to have the proper tools, shears, breaks, anvils etc. I've cut sheet metal with shears, tin snips, and pneumatic tin snips and it can be pretty tough until you get used to it. Make sure to wear gloves otherwise your hands will look like a war zone. Also, if you are using tin snips spend extra to get nice ones, it will be worth it in the end.