The 1962 Roman Missal is organized pretty much like every other missal. There are three main sections and appendices in both the front and back. The three main sections are: (1) the Proper of Seasons, (2) the Ordinary, and (3) the Proper of Saints, usually in that order.
The Propers (both of Seasons and of Saints) tell you the parts of the Mass that change relative to the day. The Ordinary is the skeleton of the Mass that mostly remains the same day in and day out. The Proper of Seasons deals with the celebrations of the Church that are moveable feasts (i.e. they are not fixed on the 365-day solar calendar). They correspond to Christmas, Easter, and all the celebrations that are calculated relative to them (e.g. Advent, Pentecost, Corpus Christi, Ordinary Time, Weeks of Easter, etc.). The Proper of Saints deals with, as you likely guessed, Saints days (i.e. days fixed on the calendar).
So, we got all the movable stuff in the front (Proper of Seasons), the skeleton of the Mass in the middle (the Ordinary), and all the stuff fixed to calendar dates in the back.
If you’re attempting to follow along every single word of the liturgy you’d place (at least) one ribbon in the Propers currently celebrated, and (at least) one in the Ordinary. As you’re following along in the Ordinary and come across a proper part of the Mass (e.g. the Epistle, or the Gospel), you’d replace the bookmark where you’re at in the Ordinary and flip to the ribbon marking the Propers.