Many houses have sloped or angled walls on the top floor, where the walls meet the roof. Having a sloped wall in your house doesn't mean you can't hang framed pictures on it. All it takes is a little more preparation and effort. The key is to secure the bottom of the frame -- as well as the top -- so that gravity will not cause it to swing down. Some home improvement shops sell hangers specially designed to hang pictures on angled walls, but you can pick up regular L-brackets and screws that will do the job just as well.
Tear off a large piece of tracing paper and place it on the floor. Lay your framed pictures on top of the paper and experiment with different arrangements until you find the one you are happy with. Trace carefully around the frames with pencil.
Attach the tracing paper to the sloped wall with sticky tape. Stand back from the wall and check that your pictures will be in the right place.
Turn your first picture frame over. Position the short side of an L-bracket along the top right edge of the frame. Insert a 6 mm to 1.2 cm (1/4 inch to 1/2 inch) screw, depending on the thickness of the frame, through the holes in the bracket to attach it to the frame. Repeat the process with another L-bracket along the bottom left edge of the frame.
Hold the frame up against the paper tracing with the brackets facing the wall. Make pencil marks on the paper where the long sides of the brackets need to be attached to the wall.
Put the frame to one side. Insert a 6 mm (1/4 inch) drill bit into your drill. Drill a hole at each of the pencil markings until you have drilled through the surface of the wall. Push a plastic wall anchor into each hole, tapping each one carefully with a hammer to secure it.
Hold the frame against the wall and align the screw holes in each L-bracket with the wall anchors. Use a screwdriver to insert a 2.5 cm (1 inch) long screw into each of the bracket holes. Tighten the screws until they won't turn anymore.
Repeat the process with your other picture frames.