SheSails has provided a library of sailing resources you can use to shore up your knowledge before getting started!
Upwind vs Downwind
This video can help you begin to understand the difference between sailing upwind and downwind:
Get yourself a three-foot piece of line and start learning knots. Here is a link to the Resources page on my website. You will find a list of common sailing knots there, with links to animated versions of how to tie them: http://shesailsseattle.com/
The Figure Eight Knot (as a stopper knot at the end of headsail sheets)
The Clove Hitch (for tying on fenders or on its side to attach to a bollard – add a half hitch when leaving the boat)
Cleat Hitch/Locking Hitch (for cleating off a line)
The Cow Hitch (for tying on fenders – add a half hitch when leaving the boat)
Round Turn and Two Half-Hitches (for tying on fenders or attaching mooring lines to posts or rings)
Reef Knot/Square Knot (for tying together two lines of similar size)
Sheet Bend (for tying together two lines of different widths)
The Bowline (for tying sheets to sails)
Animatedknots.com is a great resource for learning knots. All knot tying videos are provided by them.
The Points of a Sail Diagram
The thing that sets us apart from power boaters is our ability to harness the wind to move a sailboat. We do this by considering the direction of the wind and where we want the boat to go and then adjusting the direction of the boat and the angle of the sails to get us there in the most efficient manner possible. This chart illustrates the way we adjust the sails to do that.
The Parts of a Sail
Triangular shaped sails have three sides and three corners. Each has a name and a function.