What does it mean to have faith in Jesus Christ?

From the Sunday School study guide: What does it mean to have faith in Jesus Christ? How can we strengthen our faith in Jesus Christ?

"Learn of me, and listen to my words: walk in the meekness of my Spirit, and you shall have peace in me." (D&C 19:23)

There is so much packed in this verse!
"Learn of me..."
This is a first stage of having faith in Christ. It starts with curiosity about Him. And if you are already faithful and seeking to develop your faith, then this is a curiosity about a certain principle or commandment or scripture that you will now seek to develop (for example, keeping the Sabbath day holy).

"...and listen to my words..."
This is going beyond learning. This is starting to process what you have been learning. It is accepting what you will need to do. You will need to start living like Christ, or you will need to start being more diligent in keeping the Sabbath Day Holy.

"walk in the meekness of my Spirit..."
After learning and listening, processing and accepting, you are started to do what is necessary. You are starting to try to be like Christ and do what he commands. You are stopping your old ways and going to Church, or you are testing out focusing on the Lord all day on Sunday. This is a key step! This is the different between saying that you have faith and having faith. Faith implies action. Your action is proof, validity, and the meat of your faith.

"...and you shall have peace..."
Once you have tried out being like Christ, following his commandments, and focusing on Christ on Sunday, then you will have blessings. This may mean that you will feel the Spirit - which always brings peace. You may see a pleasant difference in your feelings, your actions, or desires. You will see that the change that you made was a good change. The blessings you receive will make your efforts worth while. These blessings will encourage you to keep doing better until you have aligned your life a little more with the gospel. This is an assurance that you have made a good decision and solidifies your faith.

"...in me."
I'm not sure what this means. Perhaps having peace in Him means that He is pleased with you. In addition to the Spirit received for keeping commandments, there is an increased satisfaction and internal sense of well being when the Lord is pleased with you. This is very desirable, and you may obtain a knowledge of where you stand with Heavenly Father and Jesus Christ if you pray and ask.