First of all congratulations. It takes time but the office is worth it.
We are on week one just now.
to help figure that out the weeks of the Psalter are linked to the weeks of the liturgical year. For example since we are in the first week of Lent if you turn to sunday of that week( Pg 32 in the uk/irish/NZ/aus edition) it tells you in red writing at that we are on psalter week one.
God Bless