Making a banner for you YouTube Channel can be a pain in the back side... because the dimension they want is just bit odd... but have no fear I slapped together a little guide
First in your program that you use to create digital art, make a canvas with the following dimensions:
2044 Pixel Width - 338 Pixel Height
This is the size of the banner that will appear on your YouTube channel, so that is the space for your logo to be, as well as any other images you can fit in that space. Set everything how you want it to be, but leave the back ground blank for now. Be sure to save your work!
Once you're satisfied, create a new image with the following dimensions:
2044 Pixel Width - 1152 Pixel Height
Here, set your background for you banner, whatever it may be, and save a copy!. Next copy and paste your banner logos from the first canvas that you made and place it about a as center as possible, you can always go back to make adjustments
Now if you have a program where you can add a new base layer, and change the canvas size so it doesn't distort the image, do so, with the new canvas size being:
2555 Pixel Width - 1440 Pixel Height
It should end up looking like this (if you fill in the new layer with a solid color)
Obviously some fine tuning is needed but hey, it works.