The Proper Belief in Allah entails worshiping Allah only, the One Who has no partners to Him in Godhood.
He has no beginning and no end to His existence.
He created all places and He does not need a place.
He existed without a place before creating the skies and earth and after creating them, God does not change. God exists without a place.
God is not like His creation in any way. He is not a body and does not have a size, shape, or any other created attributes.
Believing in Prophet Muhammad entails believing that he is the last and the best of all the Messengers of Allah. He was truthful in everything he conveyed from Allah.
All Prophets called to the Religion of Islam. Prophets worshiped God even before they received the Revelation. They never commit blasphemy (kufr) such as worshiping idols and they never commit enormous sins such as fornication.
They are also protected from committing small mean sins such as stealing one grape.