Replying to PVC pipe rails

so last year i bought 2 pvc pipes that are i think like 3 inch diameters both 8 feet long. last year i tried to screw them onto 2 work horses but attaching the rail was really tricky and it came out to be a rickety piece of shit. my dad took it apart at the end of last year and i need some advice about what to mount the rail to and how to actually mount it. i need it to be at least 3 feet high. if you guys have pics of your backyard rails that are assembled well and stuff feel free to post pics or advice. thanks