There should be a black guyline that is attached under the apex of each awning. This runs the length of the awning, and the awning connects to the sliding hook on the guyline. The end of the guyline then gets staked down.
You are thinking of more typical tents where the guyline begins at the bottom of the awning. SMD has kind of a unique design here, one that I prefer. I think the guyline running the length of the awning, underneath the awning, helps to keep the whole awning a little more taut. It also lets you push the awning up for more views/ventilation and you can select either awning (or both) to roll up.
Now for a question of my own: does anybody have advice on how to tieout the extra corner guylines for high wind? Does simply staking them to the ground help much, or do you use a contraption of sticks/trekking poles?