Psalm 119 is the longest psalm; some people like it, and others find it tedious.
You might want to finish reading these comments on the psalm prior to digging in from this link to Psalm 119.
The first important thing to know about this psalm is that each of the 22 sections correspond to a letter of the Hebrew alphabet. (Remember Hebrew is read right to left.) Each poetic line in each of the sections begins with that letter of the alphabet.
The other important thing to know about this psalm is the repeated use of the word torah, which can be understood as “teaching”, “law” or “instruction.” Other important related words are “decrees”, “statutes”, “Commandments”, “ordinances” and “word”.
The psalmist is giving us an artistic way to understand that God has revealed God’s self to us through the instructions of the Torah, or the law. The writer wants us to understand the importance of following these instructions, this revelation of God, at all times during our lives. Following God is not for sissies, it is hard work. The writer wants to be faithful to God, but knows that on his own, he cannot be faithful. The writer is aware of his/her own failings and recognizes his/her need for God’s grace and mercy.
Christians understand this to go one step farther. They understand that humans found it impossible to follow the law, and thus we were in need of a savior. A savior who would make a path of righteousness for us, that savior is Jesus. Jesus, who knows our failings and provided grace and mercy through his work on the cross.