Use a post hole digger to create the holes in your yard for the clothesline. To build a round clothesline, these holes should be in a circle. Each hole should be about 2 feet deep.
Cut several treated 2-by-4s into 7-foot-long poles using a circular saw. You need as many 2-by-4s as you have holes in the ground.
Drill holes in the tops of the 2-by-4s at the same height on each one. The holes must be large enough to install eyebolts.
Install the eyebolts into the pilot holes you drilled.
Fill each hole you dug with concrete and set in each 2-by-4. Hold the 2-by-4 steady to ensure it's standing upright.
Loop a nylon cord through each of the eyebolts on the 2-by-4s. Tie the ends off once you get all the way around the circle. After the concrete cures, your round clothesline is ready to use.