Although the scenes from Sigrud's story do not appear in order on the carving, I will go through them from left to right. The first image shows Reginn, Sigurd's foster father, decapitated among his smithing tools. Above that image and looking a bit like a dog, is Otr, Reginn's brother; he is a shape shifter. In the third scene, Sigurd is roasting the dragon's heart over a spit. The horse in the next image belongs to Reginn and it is carrying treasure. In the tree in the next scene, two birds warn Sigurd that Reginn will betray their reconciliation. Finally, there is an image, under the runic inscription, actually stabbing it from below. That is Sigurd killing Fafnir, Reginn and Otr's brother.
The Ramsund stone (or carving) is one of the coolest Runestones I've come across so far. Which one is your favorite? If there is one you'd like me to write about, let me know.