The "Anomaly" is the difference between the SST averaged over many years (for the same month) and the observed SST. This is the best way to look for unusual changes. For example, El-Nino hardly shows up in the SST data, but it shows up very clearly in the anomaly data. 1992 was an El-Nino year. Can you see the effect during that year?
Click on the map to select the month you want. After you click the map, you will enter a month at the top of the figure where it says "Time:". The image is an animation. To display a single month, click Jan,Feb,Mar,Apr,May,Jun,Aug,Sep,Nov,Dec. If you type the month wrong, you will get an error. Right click (or Control-Click for single button mouse's) to get a dropdown menu where you can download the image to your computer.
NOAA NCEP EMC CMB GLOBAL Reyn_SmithOIv2 monthly Sea Surface Temperature Anomaly