In my pattern it says to “pick up loop between last and next stitch and purl into back of this loop”. I think I’m supposed to go along my left needle as I add on stitches as it says “rib 6 stitches, make 1 stitch purlways -see above - 6 times, rib 6 stitches. You will now have 56 stitches on the needle”. HELP!!! 
Help!
That’s a M1 stitch and if you go to the Increases page, there’s a video for the knit version. Put your L needle into the yarn between sts from back to front, and purl into it as if it was a regular st, though you need to make sure it’s got a twist in it to close it up. Then work 6 sts in the rib pattern and make another one.
my mum showed me how to do it and it didn’t look anything like the video
does purling into the back of this loop make any difference?
Purling the bar between the sts will create a small hole. If you purl into the back of the bar or loop, you’ll close up that hole and the increase will look neater. It’s a fiddley kind of increase but however you learn to do it, it works.
If you pick up the yarn from back to front and purl into the front leg, it’ll twist the st, if you pick it up from front to back and purl into the back leg that will also twist it - either way is okay. The video does show the knit version, this page shows it purlwise. It’s at Lion yarn’s website so you may have to register to see it.
how do you do this? I’m sorry because it must be so simple but I just don’t get it
also should I be including a stitch (e.g. 1 knit) between 1 make one stitch?:knitting:
There is no st between the m1 stitch. You’ve just finished a regular stitch, if you stretch the needles apart a little you can see the strand of yarn between the R and L needles between sts. Pick up that st with the tip of the L needle and purl into it in such a way that it’s twisted to close up the hole. Then just go on to the next regular st on the L needle.
Why not try it the way your mum showed you and see if the sts look the way you would like? I’m partial to Mom’s way, being part of the Mom’s union.