When hard times come into your life, it is usually not the time that you can learn doctrine and become established in the faith. It is important to become established during the normal times, so that you know how to deal with the hard times.
Being established in the faith is a process that begins with the gospel. Knowing what the gospel is and accepting it gives us peace with God. Understanding that you have peace with God is the first step in having peace in your life in times of trouble.
The gospel is understanding that you are a sinner, and you need a savior. That Jesus Christ, the Son of God, came to earth and lived a perfect life so that he could be a perfect sacrifice for your sins. Trusting in that blood sacrifice for your eternal salvation satisfies God’s justice, and He grants you eternal life.