Our practice this year has been to read the Psalms, which contain 5 books, book by book. Now we return to Book V (Psalms 107-150) . The first series of psalms 111-118 are the “Hallelujah Psalms”. The “Egyptian Hallel (ps 113-118) was sung for the three great pilgrimage festivals, Passover, Weeks, and Tabernacles. The “Psalms of Ascent” (ps 120-134)  were used by pilgrims to or from Jerusalem. Psalm 136 is the “Great Hallel” for Sabbath services. Psalm 146-150 end the book with “Praise the Lord”.  Psalms 107 and 119 may be introductory psalms. 107 introduces the fifth book and 119 introduces the psalms of ascent.  Psalm 137 is untitled and unclassified. There are psalms of David in this book, 108-110 and 138-145.

You will find an introduction to the Psalms, here.

Here is a prayer from Gregory of Nazianus (329-389) who was an early Church father.

Lord, as I read the psalms let me hear you singing. As I read your words, let me hear you speaking. As I reflect on each page, let me see your image. And as I seek to put your precepts into practice, let my heart be filled with joy. Amen.
Psalm 118: A Thanksgiving. This psalm  is the last of the “Egyptian Hallel” psalms (113-118) which were sung during the three pilgrimage feasts. At Passover meals this psalm accompanies the fourth cup of wine. It is in first person, perhaps the king speaking on behalf of the people. The psalm moves between individual and communal thanksgiving.
Verses 1-4 are  communal thanksgiving.
Verses 5-21 address a variety of individual events which are a reason for thanksgiving. Verse 19 may be when the procession leader asks for admittance to the Temple. Verse 20 are the qualifications to enter. What reasons or events for thanksgiving are present in verses 5-21?
Verses 22-25 Is a communal thanksgiving.  Verse 22 echoes Isaiah 28:16.
Verses 26-27 are a blessing. Originally “blessed is tho one who comes in the name of the Lord” referred to any devout Israelite. Over time it became a messianic title.
Psalm 119: An individual petition. This is the longest psalm and has a quiet meditative tone. It is an acrostic with each of the 22 stanzas beginning with a letter of the Hebrew alphabet. Each stanza has 8 verses and usually 8 synonyms of “law”- authoritative teaching, law, word, promises, ordinances, statues, commandments, decrees, and precepts. Notice how each synonym has shades of meaning that refer to illumination, moral requirement, guidance and promise.  Notice how Torah is referred to  using words that usually refer to God.

Here are several good sources to aid your reading of the Psalms

Anderson, Bernhard W., Katheryn Pfister Darr, Understanding the Old Testament Abridged fourth Edition. (Upper Saddle River,New Jersey: Prentice Hall) 1998.

Clifford, Richard, “Psalms” in The New Oxford Annotated Bible with Apocrypha: New Revised Standard Version.Coogan, Michael D.; Brettler, Marc Z.; Perkins, Pheme; Newsom, Carol A. (2010-01-20) Oxford University Press. Kindle Edition.

Stuhlmueller, Carroll, “Psalms” in  HarperCollins Bible Commentary Mays, James L. ed.(San Francisco: HarperSanFrancisco) 2000.

McCann,Jr, J. Clifton “Psalms”,in The New Interpreter’s Bible Vol 3, Keck, Leander E. ed. (Nashville: Abingdon Press) 1996.