Trust God by trusting His word. God speaks to us through Holy Scripture. God speaks to us through Jesus Christ our Lord and the Gospel. Trust God by relying upon what He has said through Scripture, Christ, and the Gospel (1 Cor. 15:1-4).
Trust God even when you don't understand. We cannot understand all the ways of God. Trusting God is confidently believing in His ability to help us and direct us. A child is more limited in knowledge than the parents. Yet, that child can trust what the parents say to him. Likewise, our knowledge and understanding of God is limited, but we may confidently trust what He has said to us.
Trust in the Lord with all your heart, and lean not on your own understanding. In all your ways acknowledge Him, and He shall direct your paths (Proverbs 3:5-6). Lord is God's personal and covenant name. Trust God as your Lord by trusting His many wonderful covenant promises in the Bible (e.g., Jeremiah 32:40; Hebrews 13:20-21).
All relationships are built on trust. Your relationship with God is trusting Him, because He is trustworthy. His word is your bond of trust. You trust God in all your circumstances, then you can say, He is my refuge and my fortress; my God, in Him I will trust (Psalm 91:2).