You can edit the theme files in the plugin folder.
Yeah, but how? Is there a tutorial?
If you do not know CSS then you will need to learn that first. The style sheets are in the plugin folder under themes.
not sure which file to edit… I am in the /wp-content/plugins/buddypress-mobile/themes/default
I am editing the style.css but nothing is happening?
so how would i make the background black?
do I have to change both the default and ipad files?
body
{
background-color:#bc13a6;
}
That changes the color of the footer and header. I’d like to change the background of text and pics on bp-mobile page 
I can’t design you a custom mobile theme. You should create your own CSS file add it to the site root and link so when you update plugin your CSS doesn’t get deleted. There will be a few more theme styles coming one is a dark theme with dark backgrounds.