I taught myself how to knit and one of the hardest parts was finding tutorials online that showed how to knit left handed. In the end I had to learn by transposing what I saw right handed into the left handed form. To save my fellow left handers from a similar experience I have made a series of left handed knitting instructions to teach other lefties how to knit.
Step 1: Supplies
To start you need to gather supplies.
I would start out with a larger width knitting needle since they are a little easier to work with for beginners.
Step 2: The Purl Stitch
The purl stitch is one of the two main stitches used in knitting.
To start this stitch slip the needle in the right hand into the front most loop in front of the needle in the left hand.
Step 3: Loop Yarn
Now take the end of the yarn which should be hanging from the last loop you worked.
Loop the yarn from the front around the front needle and back around so it rests between the two needles.
Step 4: Release Loop
To finish you have to pull the back needle (the one in the left hand) out, leaving the new loop on the back needle.
Start by pulling the back needle down, so the yarn slides up to the top. Then take that piece of yarn and loop it over the front needle.
Slowly pull the back needle out, allowing the yarn around it to go free.
Pull taunt on the new loop you have on the right hand needle.
Step 5: Repeat
With one loop done it is time to do the rest.
Depending on your pattern you may only do this knit stitch, or alternate between this stitch and the other stitch called the purl stitch. Just pay attention to your pattern to understand what stitch is needed where.