This is not "deep murky waters" - this is an absolutely basic, fundamental concept.

As Patrick says, you really need to understand these basics before you can proceed - you cannot build a house before you've laid good foundations.

Anyhow, the format of the data from the DS1620 is illustrated diagramatically in Figure 2 in the Data Sheet, and further illustrated with example readings in Table 3

You should be able to work out what's going on from there...