Gazebo replacement covers 10×10 provide shade and protection from the rain for them inside. But continued exposure to weather and wind causes the gazebo cover to fade and rot, and must be replaced much earlier than the rest of the gazebo. If you cannot copy the old gazebo cover to create a new one and you have good basic sewing skills, you can make your own pattern and sew a new one.
Measure the circumference of the lowest area of the gazebo replacement covers which will be shaded by the lower edge of the new cap using a measuring tape. Use a partner to help you wrap the tape measure around the structure. If the structure is quite large, you may need to measure one section at a time, and then summarize the results. Measure the distance from the lowest point to be covered by the bottom of the gazebo cover up to the point where the roof angles begin. Record this as the lower flap measurement.
Measure a part of the roof: Hold the end of the measuring tape at a lower corner of the roof, and measure over, parallel to the gazebo foundation or ground to the next lower corner of the roof. Register this as eaves. If the gazebo has a square footprint, you do not need to measure another side. Cut a portion of paper from the paper roll length to the eaves. Using a staircase if needed to easily reach the ceiling, align that portion of the paper along the ceiling base and secure it in place. The paper section should rest against the ceiling of the gazebo, and the straight lower edge of the paper should align.