Allah tells us that He is the Creator of all things. He created the heavens and earth and all that is between them in six days, then He rose over the Throne -- we have already discussed this matter elsewhere.
(You have none, besides Him, as a protector or an intercessor) means, only He is the Sovereign Who is in control of all affairs, the Creator of all things, the Controller of all things, the One Who is able to do all things. There is no Creator besides Him, no intercessor except the one to whom He gives permission.
(Will you not then remember) -- this is addressed to those who worship others apart from Him and put their trust in others besides Him -- exalted and sanctified and glorified be He above having any equal, partner, supporter, rival or peer, there is no God or Lord except Him.
(He directs the command from the heavens to the earth; then it will go up to Him,) means, His command comes down from above the heavens to the furthest boundary of the seventh earth. This is like the Ayah,
(It is Allah Who has created seven heavens and of the earth the like thereof. The command descends between them, ) (65:12) Deeds are raised up to the place of recording above the lowest heaven. The distance between heaven and earth is the distance of five hundred years traveling, and the thickness of the heaven is the distance of five hundred years. Mujahid, Qatadah and Ad-Dahhak said, "The distance covered by the angel when he descends or ascends is the distance of five hundred years, but he covers it in the blink of an eye." Allah says:
(in one Day, the measurement of which is a thousand years of your reckoning. That is He, the All-Knower of the unseen and the seen,) meaning, He is controlling all these affairs. He sees all that His servants do, and all their deeds, major and minor, significant and insignificant, ascend to Him. He is the Almighty Who has subjugated all things to His control, and to Whom everybody submits, and He is Most Merciful to His believing servants. He is Almighty in His mercy and Most Merciful in His might. This is perfection: might combined with mercy and mercy combined with might, for He is Merciful without any hint of weakness.