The symbols are as follows:
Triangle that slants this way / - knit 2 together
Triangle that slants this way \ - slip 1 stitch knitwise, knit 1 and then pass the slipped stitch over the knitted one
Triangle that slants both ways - slip two stitches knitwise, knit 1 then pass the two slipped stitches over the knitted one
Circle - yarn forward and over the needle to create a new stitch.