Ex 7:1 So the LORD said to Moses: "See, I have made you as God to Pharaoh, and Aaron your brother shall be your prophet.

2 "You shall speak all that I command you. And Aaron your brother shall speak to Pharaoh to send the children of Israel out of his land.

Moses felt inadequate about his qualifications in going to Pharaoh. Now, God is addressing that issue. Who is Moses? He is the man who God made "as God to Pharaoh!" Moses was God's representative. God reveals His will to him, and so, in effect, in this capacity, he was "God" to Pharaoh. Here God Himself is qualifying Moses for the job. 

The Pharaoh's back then were viewed as gods. In order to create an impression of their divinity, they usually spoke through a spokesman. This create a sense of distance which kept up the impression that they were divine. 

Now, Moses is going to do it to Pharaoh through Aaron!