pascha bchochma
If you are curious about these types of things then you will love the Artscroll Interlinear translated Siddur. It has explanations before each Tefillah and great translations as well as some added explanation of what specific words or concepts are. I can’t compare my Davening before, to after I got this siddur. Consider it a MUST BUY. (They also just put out a new Siddur, that may be a good choice as well but I didn’t look into it so check at Eichlers or wherever you go) you could probably also see samples online at Artscrolls website.
I just looked it up in my siddur, in short, the Shir was said by the Leviim daily during the Tamid shel shachar. We say it as a memorial to the Bais Hamikdosh. Each one represents the importance and significance of that day of the week and is full references to what was created that day of the week. We start off Yom Rishon (sheni…) bshabos to be mekayem the Mitzvah to remember Shabbos always.
Now go buy that Siddur you’ll thank me!!! 🙂