Your wallpapers are copyrighted and the copyright belongs to you. You don’t need to apply for it or register it, it is yours automatically. If you want to make it available on your website, just choose a license and put in a line saying “This graphic is licensed according to the XXXXX license” with a link to the text of that license. That’s pretty much all there is to it.
Ah, sorry, didn’t notice that part of the question. That gets into murkier areas of “derivative work”. Are the Haiku logos covered by a license? Then read that carefully and it will tell you what you can and can not do. If it is not licensed then you cannot distribute it without explicit permission of the owner of the logo (presumably Haiku, Inc, but check that.).
The easiest way to get around all this is to transfer the copyright of your wallpapers to whoever owns the logo, and then continue to distribute it on their behalf. If they are interested, of course
Disclaimer: I’ve read up a bit on this, but I am not an IP lawyer.
That means using the Haiku logo should have the ® somewhere, and somewhere the follow statement should be visible:
“Haiku® and the HAIKU logo® are registered trademarks of Haiku, Inc. and are developed by the Haiku Project”.
You may resize the logo provided that
The aspect ratio is maintained
A size greater than 150 x 50 pixels is used
When using a logo with a transparent background, to use the correct logo
Dark background : White wordmark
Light background : Black wordmark
All other modifications are not allowed
Cannot pair the logo with external elements to create the appearance of another visual entity (eg " News")
Notice that using the trademarked Haiku leaf or Haiku background leaf allow more graphical modifications, though.
Regarding your work, you’re able to licence it as you want I guess. What’s you can’t do is not respecting the registered Haiku trademark by attempting to hide who own this mark, to let people think you own it,or trying to associate with something without permission from Haiku Inc., etc. Aka trying to abusing the mark.
If you follow the usage requirements above, it should be fine.
Oh, I forgot it: you will find the official Haiku logos and Leaf and background Leaf - (and other derivative artworks made by Haiku Project, which has a explicit permission to use Haiku marks that way) in Haiku source code tree, here :
There is PNG versions, SVG versions and Wonderbrush (those without extension) format, aka its native format.
Several variants are available for light or dark background, in different sizes etc.