Hi Donna.
Welcome to the world of skinning. The tutorials you have read will prove to be very useful to you as skinning does not really lend itself to a "hand's on", as you put it, learning experience. Skinning is process that takes many, many hours to complete a skin. Expect to dedicate well over 100 hours to your first skin. Learning is done through trial and error, as well as periodic critiques by posting your work here. I will do my best today to get you to a point of posting your first pics of a work in progress.
The first step is to get the default skin folder of the plane you want to skin from the AHIII game (DX 9 only). Right click on the plane you want in the hangar and click "Save Default Skin". Once downloaded, you will find a folder for the default skin inside the "Skins" folder in the AHIII directory on your hard drive. In that folder you will find all the different files for that skin. Also now is the time to make the folder to put your edited files into so that they appear in the offline game and skin viewer. Name your folder the same as the one you downloaded and add "_1" at the end. Inside this folder create a text document that has basic skin name, for example, "P51D" and in that document give your skin it's title so that you can find it in game easily. For example: "Donna's Skin". Don't forget to save.
Find the diffuse map (base skin file) in the downloaded file. In the case of the P-51D, the diffuse map is "P51D.bmp" The other planes follow a similar naming scheme. Open this file in your editing software of choice - Adobe Photoshop, Paint Shop Pro, or GIMP. All of these programs use "layers" that allow you to work above the base image. A finished skin will have over 50 layers to handle all the paint, markings, weathering, and plane structures.
The first thing you want to do in the editor is to create the file for your work so that is saves all the layers correctly. Open the diffuse map file .BMP and save as a .PSD Photoshop file. All AHIII skin diffuse maps are 32 bit RGB mode. I also like to create a file on my desktop for all my PSD files.
Now you can begin making your new skin.
Where you want to start is by creating a layer above the default image(which you should never edit directly - and it should always be the bottom layer). On this new layer you want to trace all the panel lines seen on the default skin. I usually use a color that will not blend in with the default skin so I can keep track of what I've done. Once finished will all the lines you will change the color to black. Title this layer "Panel Lines" or something similar.
Repeat this same process for the rivet detail on a new layer.
Use these layers to experiment with the tools for drawing solid and dotted lines and when to use or not use anti-aliasing for your panel lines and rivets.
Also pay attention to where you may be able to copy a section of completed work and paste it elsewhere on the skin to save time.
It is also a good idea to gather reference photos and line drawings of the plane type you are making. Use these to check the accuracy of the lines you created and make any necessary adjustments. Many default skins have flaw in the placement or sizes of panels. It is easier to correct these now if you choose to, than later.
Once you are happy with the panel line and rivet layouts you can begin to lay down your basic paint scheme. You just need a good neutral color as a base for the other effects to come.
Do not hesitate to ask questions here, as no tutorial will cover all the minutia of making a good skin and making it work in the game properly.
