In short
Creation
God created the heavens and the earth, and in six days made all living things. He rested on the seventh day. This is His own account of how life began, and it shows His purpose and care for everything He made.
Read it in the Bible
Genesis 1; 2; Exodus 20:8-11; Psalm 33:6, 9; Hebrews 11:3
This is a short summary. The church's full statements are at adventist.org, and our pastors are glad to study any belief with you.