We had to replace a rotting picket fence. Luckily the 4 x 4s cemented into the ground were still very much in tact and so that definitely made it easier to put up the new fence sections.
Plan ahead measure and decide how many fence sections you will need to order.
Step 1: Remove and discard old fence panels
Step 2: Unload measure and cut sections if there is a need for it. There was for us a few cuts to fit the panels in.
Step 3: Screw panel sections onto the posts
Step 4: Let the fence panels dry as the treated wood will need to be dry in order to paint.
Step 5: Paint the fence panels