Autodesk Inventor iDoor Tutorial
Page 9 - Sketching the Rails

Zoom in on the lower right hand corner. If you are not sure which is which, or up from down, the origin plane should be going in the Y- direction or downwards.

You can also pause your cursor over the Stile Profiles sketch in the browser which will highlight the sketch till you remove the mouse. It should look like this...

Now that we are certain that we have the right corner, repeat the process that you used to create the Stile Sketch Plane. Get the Work Plane
tool, then click on the lower right point, then on the exposed YZ pane to create the new plane. Name it Rail Sketch Plane. Because all of the geometry has been created in the Y- direction, this plane will also face downwards.

 The next step is to Create 2D Sketch
 on this plane and call it Rails Profiles. Project the same point that you just used to create the plane as well as the one in the center top. Click on the View face tool located under the View Cube, and click on the YZ plane in the Origin folder to look directly at the sketch (normal to it's plane). The leftmost projected point is the start for the bottom rail sketch. Draw the top and bottom rails exactly like you did for the stiles except use the bottom_Rail_Width and Top_Rail_Width parameters for the longer (width) dimension, and don't forget that the bottom rail sketch goes downward and to the right, and that the horizontal and vertical constrains will be the reverse of what it looks like they should be. Also, when you start dimensioning, do the upper Dimension
with the formula first as it should still be in the 'recent' list.

(Late) Tip; to keep your sketch from flipping out (as much as possible), draw it close to the correct size to start with by looking in the lower right corner at the status bar while sketching---it gives angle and length info in real-time.