Hi nordzway, so to orient it you need to have 3 snap points you can identify on each object.

Your object only has 2 "natural" snap points on each side so you'll have to set up a third point, if these objects were copies of each other it would be easiest to mark a third point to the side using Draw curve > More > Point before copying it so it was all ready to go right away. For your case here you'd instead need to do something repeatable on each piece to set up the third point, here I've drawn in a line using 2 end snaps:



Then I created a second line starting at the midpoint and using "Perp/Perp" snap like this:



Then to simplify the explanation a little bit I trimmed the first line so I've got this:



So now the 3 points are like this:



You can now use Orient on your objects, and if you just snap each orient origin point onto the juncture of those lines the default orientation method will probably do what you need with lines at 90 degrees to each other like I've set up here. Click on any one particular axis to mark it as the "primary axis", it will then get a dot on it. Then if you grab one of the other axes you can drag them around the marked one if needed. Here's a demo video:



To do it in the manual way you would turn off "Align to objects" mode for each pick (because you're going to be doing all the orientation yourself so just turn off the initial alignment to surface normal and curve tangents), and then place the origin at pt#1, drag the x axis and release it at pt#2, and drag the y axis and release it at pt#3.

It simplifies things if you set up 2 perpendicular lines as above though.

- Michael