Okay, so this is a first for me...
The reason the "*" are there is because of the fact that the way I do it may not be the best, and might be the worst in reality. So, with that said, let's do this...
(Also, note, I'm using HellFireKoder's fine tuner mod for this(sorry IOS))

Step 1- Cockpit.
You're gonna want a cockpit for your plane, so choose anyone. For this one I'm gonna have a historic cockpit.

Step 2- Fuselage.
Get a fuselage, then turn it to where... hmm... let the image explain how to orient it...

Step 3- Edit said fuselage
Edit the fuselage to your preferred size. I'll do it to a width of 5 and height of 2. I'd nudged it up to hide the base of the cockpit.

Step 4- Circular
On the fuselage, change the edges to Circular in its settings. This makes the shape of the wing. Also, I changed the length of the fuselage to 1 instead of 2.

Step 5- Wings
In this step, this is how I do the wings, you don't have to follow it exactly, but it comes out beat for me. Let the image show what I mean. First wing is structural, while the second wing is a primary wing. Since primary wings are so weak, I make them small, and keep them close to the center of the plane.

Step 6- Wings 2
This part is where you cover the wings with fuselage. For this part, you'll need the mod mentioned above. For this, I place a fuselage over the wings by clicking "Add section" were the option to change the edges are. After that, open the mod menu, then click "Scale tool". Open that, then change the length to somewhere between 1.01 and infinite( but something manageable). You can stretch it multiple times if needed. It's okay if the wings poke out, just change either the fuselage "wing", or the actual wings.

Part 7- Repeat
Repeat step 6 as many times as you can if you want, or make it as short as you want. It's your choice.
Part 8- Wings 3
For this, you'll need to use the nudge tool in the mod menu. To move the COL behind the COM, you will need to nudge several structural wings into the center of the fake wings. I recommend copying the Y coordinates of the fake wing, and pasting it in the Y of the fuselage after you place it down.


Step 9- Mirror
To mirror, well, you should know how to do that, but when you do, the fuselage wing won't connect, so you'll have to manually reconnect every fuselage wing on part opposite of the mirrored half.
Step 10- Wings 4
For elevators, you should place them near the ends of the wing, or you can add a extension off the back for an elevator. If you chose the first option, then copy the instructions from part 8.

(Basic extension for elevators)
Step 11- Vertical stabilizer
For this step, you need the mod, and go to "Stretch tool". Change every option in X Y and Z somewhere between 0.99 and infinite as long as it's a decimal. Do this until you can't see the stabilizer.
Step 12- Engines
For this, choose an engine. It's recommended to choose a jet engine J90 and up, but you can use a prop for a slower flying wing. For this, im gonna use a J90. After you pick, place it over where you want it, specifically on the front of the craft. Copy the Y coordinates of the fake wing, then paste it into the Y coordinates of the engine. It should move to the center of the wing now.


After that, you can do the same with fuselage blocks to make it transition better into the wing.
Step 13- Tweaking
Now that this is finished, try to fly it after checking COL/COM to adjust it.
Step 14- You did it! You made a basic flying wing! Now celebrate by... well... what ever you do!