How to refinish this wood and aluminum...

[brad hays]

My back door step could use some sprucing up but I'm not sure how to go about it. I would imagine the wood pictured is treated and the metal is aluminum. How would I go about resurfacing or finishing both these surfaces to get them to look some better?

The painted white part on the left is actually a different surface a couple inches below the unpainted wood step.

Thanks

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