@Taissa, yes I am checking it. I was doing as Aliia mentioned in a previous comment:

Quote from AliiaLuke, try adding background into the block decorator styles in join_index.html (ow_systemplugins/base/view/controllers).  Something like: style="background-image:url(ow_static/themes/youractivethemenamehere/images/yourpicturenamehere.png)" .

Please note that any changes you do in .html files will be erased if you update the software. Make a copy of the original file and save it somewhere before editing to back yourself up. 

html body.ow.base_sign_in {
background: url("imgs/nature-landscapes-orchid.jpg") no-repeat scroll 50% 50% / cover #242442 !important}

hey Chris_W

Take a look at this post, http://www.oxwall.org/forum/topic/5145?page=1#post-136541 it may help with your issue....hope it helps!

Wilson

Guys, thank you for sharing the solution.
Krishnakumar, have you managed to fix the issue?

Wow! It's working :) @Chris_W, @Krunch, @Taissa, @Wilson Thank you all for helping.

@Everyone who are not techies, this thread can be used for 'changing landing page in oxwall', 'changing landing page in Oxwall Darklets theme', etc. Codes needs to insert on css under Edit theme. Since I am not techie by mistake I have inserted codes in "join_index.html" adding block controllers. But that did not work.

Great! I'm going to mark this thread as Solved.