Tear your fabric into strips about 4cm wide, going with the grain (parallel to the selvedge). Start by making a small cut and then grasp both sides and tear firmly.
Fold back about 0.5cm along one long side of each strip and press with an iron. You can do both edges, but one is enough since the raw edge will be hidden.
Start at the top edge of the shade. Apply glue, stick down a strip with the pressed edge facing left, and let it hang straight. Then glue it at the bottom. Repeat with new strips, overlapping the raw edge of the previous one with the folded edge of the next.
Place your final strip without glue, then fold the raw edge under so it aligns neatly with the first strip. Press it flat, then glue it into place like the others.
Trim the ends of each strip neatly. Add glue just inside the top and bottom edges of the lampshade, and tuck the excess fabric to the inside. Use pegs or clips if needed while it dries.
Optional: To create a tidy finish, glue a strip of folded fabric, bias tape, or ribbon around the top and bottom edges.