Lord, I Call consists of four psalms accompanied by hymns (called stichera), 4 to 10 in number, which are prescribed for the day. The stichera are found in the service books called the Octoechos, Meniaon, Triodion, and Pentecostarion. They are inserted between the last few verses of the psalms of Lord, I Call.* For example, let's suppose 6 stichera are prescribed for a given day. In that instance we would say that "Lord, I Call is sung on 6." Here is how the stichera would be inserted in that case:
(a) In the service book the four psalms appear one after the other, so that the text forms a continuous reading. The 10th to last psalm verse from the end of the reading is marked "on 10" (this is printed just before the psalm verse). The 8th to last psalm verse is marked "on 8," and so on.
(b) The text of the four psalms is read in entirety, but stopping after the reading of the psalm verse that is marked "on 6," since there are 6 stichera to be sung.
(c) The first of the 6 stichera is then sung. This is followed by the next (5th-to-last) psalm verse, the next (2nd) sticheron, the next (4th-to-last) psalm verse, the next (3rd) sticheron, etc. The last sticheron will follow the last psalm verse.
(d) "Glory to the Father . . ." is then read.
(e) If there is a "Glory" hymn for the saint, it is sung.
(f) "Now and ever . . . Amen." is then read.
(g) The final sticheron, often a Theotokion, is chanted.
For more about the specific stichera that are appointed to be sung at Lord, I Call on various days, see the Tables that supply this information.
*Occasionally there are extra stichera, introduced by special verse(s). On the feast of Annunciation at vespers (for March 26), 11 stichera are sung. The first 10 are inserted the usual way, beginning after the 10th-to-last verse of the the psalms of Lord, I Call, in order. Then the verse "He makes His angels spirits and His ministers a flame of fire" is chanted, followed by the 11th sticheron. On the fifth Wednesday of Great Lent (at vespers for the fifth Thursday), Lord, I Call is sung on 29 -- the usual 6 stichera are followed by 23 more by St. Andrew of Crete. We begin inserting the stichera after the psalm verse "Sinners will fall into their own nets..."; when the psalm verses are used up, we chant "Glory to You, our God, glory to You" before each remaining sticheron. A final, 24th sticheron of St. Andrew is sung as the Glory verse. (If the Presanctified Liturgy will not be served on Wednesday, Lord, I Call is sung on 26 instead of 29).