With the railings tool, you can

When you create a railing, rails and balusters are automatically placed on the railing at evenly spaced intervals. For information on editing baluster and post placement, see Controlling Placement of Balusters and Posts.
The shapes of rails and balusters are determined by the profile families loaded in the project. See Railing Properties.
Continuous rail components of the railing system (top rail and handrail) can be edited, and extensions can be added and modified, as needed. See Modifying a Continuous Rail.
Set up automatic railing placement for stair or ramp creation.
Place a railing on a stair or ramp.
Create a railing by sketching the railing path.
Modify a railing by editing the path, railing structure, and railing properties.
Edit properties for a top rail or handrail.