So now you have a pile of wooden arches. Well done! Since you have them, you should install them somewhere. How you choose to install them is ultimately up to you but I will suggest the following way...



Start by clamping the two end arches to your structure. Each end of each arch should sit on your walls at a right angle to them. You can see how the end arch is clamped in the picture and the others are upside down, waiting to be put into place.



With your two end arches clamped, use screws to toenail* them to your wall frames.

Now you can place your center truss into the slots at the apex of either arch and screw it into place. The ends of the truss can go beyond the end arches or they can stop at each arch, that depends on your preferences.

*Toenailing or skew-nailing is a popular technique that carpenters use regularly to fix two timbers together by slanted application. The fasteners (nails or screws), used in pairs, are driven in on opposing angles. This locks the timbers together, to create a stable framework, e.g. in stud walls (partitions) or roof framing. The angled nailing makes later dismantling difficult or destructive. One of the most common places to toenail a framing member is where a rafter meets the top plate of a wall at the birdsmouth. Alternatives to toenailing include the use of hurricane ties, joist hangers, and other engineered steel connectors that permit nails to be attached perpendicular to a member's surface.

When toenailing, nails can be driven from the inside or outside of the joint, depending on access available to use the hammer. Skew nailing is also a technique used by other woodworkers, for example a drawer or box can be glued and skew-nailed with finer nails or panel pins. Skew nailing will fasten the joint, while the glue sets, avoiding the use of clamps. A variation of toenailing is to use screws for the same purpose, which might be called toenailing or toe-screwing. - Wikipedia