Why can't you get the alumi.ium post?
Hi Brian: Unless you are going to put the wooden supports into cement, I'm afraid, even if they're treated, that they will rot in a few years. So, use cement. There is cement that you pour into the hole dry and add water. No stirring or mixing. Here is a site for this: https://www.homedepot.com/p/Quikrete-50-lb-Fast-Setting-Concrete-Mix-100450/100318521
Here's a site that should really help: https://aluminumfencesdirect.net/fence-installation-precautions/
Brackets attach to the ends of he aluminum fence rails and screw into the wood posts.
Not an answer. They are asking how.
How big do you want and length