The SMC solenoid comes with 2 gaskets. The O-Ring-ish one fits snugly in both the top and bottom pieces of the solenoid. This will be your best bet to prevent leaks. The flat one will work, but is not advantageous. Don't use both, you almost definitly will have a leak.
As for the Festo valve, I'm not sure what you need to assemble, they came pre-assembled. Or do you mean how do you connect the tubes for the flow of air?
If I remember correctly, the solenoid's are labeled:
Code:
|¯¯4¯3¯¯|
| |
|_5_1_2_|
When unpowered, air will flow from 1 -> 3, and 4 -> 5(exhaust).
When Powered, air will flow from 1 -> 4, and from 3 -> 2(exhaust).
The unused number in the above states are plugged from air flow.
Ports 2 and 5 do not have a fitting, nor do they need one. If you are able to force one in there will be a leak and there will be damage to either the solenoid or the fitting. You can not order additional fittings that thread with the Festo solenoid nor are additional fittings in the kit.
Make sure 1 is where the Pressure is coming from. Or you won't have happy results.