I want to build several (about 9) 4x7 feet trellis sections to divide a walkway visually from the pool. I am a real newbie and have only built a fence along the steps around a deck and a frame for a tile table top, so I do welcome advice. I want a rectangular outside frame with about 3-4 vertical and 3-4 horizontal pieces in some artistic rectangular design inside. After I'm done, I plan to use wire ties and hang 4x7 sections of willow/reed fencing on one side of each section to hide the pool.

I need to know what size and thickness of steel tubing I need for the outside frame and inside decorative sections. I don't want over kill, but I certainly do not want the sections to bend when the wind blows.

Also, how should I anchor these into the soil? Set them in cement? Pound each section into the ground? Set pipes with inside diameter the same size as the outside diameter of the tubing into the ground and then just stick the trellis sections into the pipes? That appeals to me so I can lift them out to paint or whatever, but I don't know how long the extra part that goes into the ground needs to be to keep the trellis sections upright and secure. Two feet? Anyone willing to give some advice?
Thanks in advance!