This is a VERY basic description of how to use the above forecasts. For more detailed information go to http://magicseaweed.com

Swell and wind are the 2 important things here, lets start with Swell :

Swell is read like this : x feet @ y seconds.
Here is an example of good big surf 10ft @ 20 sec
Here is an example of small bad surf 10ft @ 10 sec

As you can see the swell size is the same in both cases, however the time has changed. The longer the time, the closer the actual waves will be to the size given.
ie : 10ft @ 20 sec will mean that the actual waves will be close to 10 ft whereas 10ft @ 10 sec will probably mean that the actual waves will only be about 3-4 ft

Wind is also very important. You should know what wind your local spot works off .
ie : Durban works off a Westerly wind. So if we had a report like 7ft @ 22 sec with a 10 MPH South West wind, the surf should be really good, whereas if the report was more like 9ft @ 8 sec with a 25 MPH North East wind, the surf will probably be terrible.