Brush wood stain or water sealant on the cedar planks and rod to help prolong the life of the wood. Cedar, while naturally resilient, isn't weatherproof. Allow the stain or water sealant to dry completely before building the stand.
Measure 1 inch in from an end of one of the planks and drill a hole completely through the plank. Drill a hole through the other cedar plank in the same manner.
Apply wood or craft glue generously onto one end of the dowel rod and insert the glued end into one plank through the hole you drilled. This may require some fidgeting to get the rod to fit, as the hole will be snug. Allow ample drying time for the glue.
Hammer one of the planks into the desired location in your garden. If you have particularly hard soil, use a utility knife to whittle the bottom of the plank into a point for easier insertion. Drive the plank about 6 to 8 inches into the ground.
Place the other wood plank beside the first plank, spaced apart the same distance as the 2-foot dowel rod, minus 1 inch. Insert the free tip of the rod, coated in glue, into the hole of the second plank, thus forming the flag stand.
Drape and secure the flag on the dowel rod using the attachments that came with the flag.