The purl stitch in knitting is another of the basic stitches. It is the opposite to knit and if all the rows were knitted in purl then it would look like the picture above. In patterns this stitch is abbreviated to just a "p" sometimes it has a number after it and that would indicated how many stitches to do in purl.
By alternating this stitch with the knit stitch then a totally different appearance is given to the finished work. As purl is lets say the opposite to knit then the loops face the same direction. This gives the knit side a smooth "V" look and the purl side a bobble look as in the first picture.
To start knitting, all the stitches need to be placed on the needle this is known as "casting on". When they are all on the needle then the first row can be started. In the description the first needle is the one with the stitches on it and the spare needle is the one without stitches at the beginning.
Unlike when doing the knit stitch the strand of wool is brought to the front first and should be done so whenever a purl is needed like in rib. Then the spare needle goes into the loop at the front of the first needle..
Having the wool already at the front of the work makes it easier to take the strand of wool and loop it round and in between the first and spare needles. Try to keep the strand of wool fairly taut and you will see it forms a loop on the spare needle.
If the wool was not brought to the front of the work first then the stitches would look twisted and it would give a extra strand on the needle.
Try to keep hold of the strand of wool, using the ring and small fingers in the hand holding the spare needle, bring the spare needle back under the first needle keeping the woollen loop on the spare needle. As the spare needle goes under the first needle gently push the first needle back out of the loop so that it remains on the spare needle.
The first purl stitch has been completed now continue along the rest of the stitches until they are all on the spare needle. All the knitting of the purl is at the front of the work whereas the knit is at the back.
This type of knitting stitch along with the knit stitch will give other patterns as well such as rib, moss stitch and basket weave which all have their own individual look.
Try making up a mixture of your own and see what it turns out like.