Drape your sheet across the center of your furniture piece. Pull at the edges of your sheet until it completely covers the piece of furniture. Align the edges of the sheets with your furniture piece's edges, creating a very straight, centered drape.
Tuck the sheet into the furniture along any crevices or folds. Situate the sheet deeply inside the folds. Insert the dowel or dowels into the folds to hold the sheet in place.
Cut your additional sheet into two equal pieces if you're covering a very large sofa. Drape each sheet piece into over each uncovered arm, and tuck them into the arm crevices.
Fold any loose sheet edges at the bottom of the furniture piece underneath the piece. Secure them with T-pins, placing one every few inches.