Doing It Faster
Hold Ctrl and select the component that you want to move and the component that you want to remain stationary, then click Tangent in the Assembly group on the Design tab.
Reversing the Sense of a Tangent Condition
Right-click a Tangent condition in the model tree and select Reverse Sense to align the components to the opposite side of the alignment plane.
You can also modify the Reversed value to True or False in the Assembly Condition section of the Properties panel.