I want to pour some concrete next to my house but just above my foundation wall is a wooden header (probably 2 - 2X8s on edge) that is about 8 inches tall. I wanted to pour the concrete up to the bottom of my door but this will cover the wood. Is this a problem? Someone told me that the concrete would rot out the wood. If this is true can I cover the wood with something to prevent rotting?

Thanks

You can treat the wood with Cuprinol, but no matter what preventive measures you take, water will eventually find a way into the structure. After 10 years or so, you will have a rotten floor, joists, & door threshold.
I have had to repair several houses where this occurred, & it isn't cheap.