To install a vinyl fence, stake out the fence line, and tie a string between the stakes. Center the posts between the stakes, and dig a hole 10 inches in diameter and deep enough to house 1/3 of the post. Secure the posts with gravel and concrete, and install the rail brackets on the fence posts. Set the fence panels into place, and use screws and adhesive to secure the panels.
Install the corner posts first, and tie a line between each of the main posts to serve as a guide for installing the other posts. To secure each post, pour 6 inches of gravel into the bottom of the hole; set the post into place, and pour concrete into the hole. Use a level to ensure the posts are plumb, and adjust the posts as needed before the concrete sets.
Attach the vinyl fence panels to the main fence posts after the concrete sets. Install the rail brackets on the fence posts according to the manufacturer's instructions, and then place the fence panels onto the brackets. Secure the fence panels to the posts with screws.
Glue the top pieces to the posts using vinyl adhesive. Apply the adhesive to the area where the top piece hits the post, and hold for 10 seconds.