I am really struggling with fishermans rib. Every time I try I seem to end up with extra stitches also my stitches seem to be in triangles instead of obvious separate stitches so I am clearly doing something wrong I just dont know what! I’m very new to this knitting lark and I’m getting very confused 
Here’s a tutorial with pictures to show the k1 below stitch, you have to make sure both sts slip off the L needle so you don’t accidentally knit into both of them. It also takes several rows for the sts to look like the pattern. It can help to pull your work down so the sts snug into place.
Here is a video. http://www.wonderhowto.com/how-to-knit-fisherman-rib-stitch-314267/
I was having a hard time figuring out how you would be getting triangles. So I did more hunting. There is a German version done with yos. In case, that is what you are working. Here is a link.
Thanks for those guys, problem is those tutorials dont show you how to do it when you’re on the first few rows and everything looks the same especially to a novice like me!! I will keep trying and I’ll take some pics of my triangles if they appear again haha. As far as I know I am doing it like the vid on youtube is but clearly I’m not. Will I ever be able to knit while watching TV???
When I do Fisherman’s rib, I knit the first row, then do k1, k1b across the sts ending with a k1. The next row is k2, k1b across and end with k2. I keep repeating these rows which makes it reversible. You could knit all sts on the WS row instead, like the first row. It’s tricky to remember to alternate sts, if I have a large number of sts I sometimes get off, knitting 2 instead of k1, k1b.