The hard part is to dig out the old post/concrete footer, install new post/
re-pour new concrete footing or pour with bracket. Make sure the posts are
level across the length of the field. Nail in top/bottom horizontal 2x4
support beams and then screw in the fence panels.
You'll need a good set of saw cause there'll be a fair amount of cutting.
Knocking loose the old concrete footing is heavy labor with sledge hammers,
suggest you hire a day laborer to help.