At first it’s confusing but once you get it it’s ok. First you have to figure out what week of the psalter we’re on (Week IV right now). Since it’s ordinary time you just pray the morning and evening prayer straight through in the morning and the evening. If it were advent, or lent you’d pray the psalms from the week we’re on and the readings and everything that follows the readings from the proper season that the Church is in. You just go through the four week cycle and you always begin at Week one on the following days, the first Sunday of Advent, Monday after the Baptism of the Lord, First Sunday of Lent, and Easter Sunday. On the Monday after Pentecost you go to the week indicated on the chart (page 15 in my book) depending on what year we’re in. I also recommend this book:
amazon.com/Practical-Guide-Liturgy-Shirley-Sulliavn/dp/0899424848/ref=sr_1_11?ie=UTF8&qid=1316193193&sr=8-11 it helped me when I first started. Also, you could talk to your priest or deacon who can help you understand it as well. But like I said once you get it you’ll get it, one day you’ll have an “ah ha” moment and it’ll all become clear. Good luck!!