Toolbar: 
Constraints toolbar 

Menu: 
Add menu > Geometry submenu> > Constraints submenu > Add Parallel 

What to do: 
Click Add Parallel Constraint, then click:
 or 
 or 


Result: 
 or 


Notes: 
None 
Before 
After 
Select: Result: 
In SelectionWindow & GeometryTree as... 


The Two Lines becomes Parallel 
Parallel 

The Line becomes parallel to the Y–axis 
Parallel 

The Line becomes parallel to the X–axis 
Parallel 