BuddyPress.org

1st:

is the child theme folder in the wp-content/themes/ folder

The child-theme folder is, were you have placed it.

The child-theme folder should be on the same level of your folder-structure as your parent-theme (“comprehensive theme”)-folder.

E.g.:

• I have a folder wp-content/themes/reddle – for my parent theme
• and a folder wp-contentent/themees/reddle-child – for my child.theme

2nd:

Theme Name: BuddyPress_GSN

Template: buddypress

I don’t know, whether it should work your way as well, but I do not refer on the BuddyPress-theme, rather on my WordPress-parent-theme – so, in my case the style.css of my child-theme beginns with:

/*
 Theme Name:   Reddle Child
 Template:     reddle
*/

3rd:

You have to connect child- and parent-theme – in my case it is (as next line of my style.css) on the one hand:

@import url("../reddle/style.css");

And on the other hand you need a functions.php within your child-theme-folder as well. In my case it starts with:

<?php

/**
 * Enqueue stylesheet
 */
function reddle_child_theme_stylesheet() {
	wp_enqueue_style( 'reddle-child-themestyle', get_stylesheet_uri() );
}
add_action( 'wp_enqueue_scripts', 'reddle_child_theme_stylesheet' );

4th:

Finally you have to activate your child-theme. You do this within the admin panel of your WordPress-installation:

http://1a-spielwiese.de/wp-admin/themes.php

In the case, that you have installed WordPress MultiSite, you have to activate it on the network level as well:

http://1a-spielwiese.de/wp-admin/network/themes.php

Cfr.: https://buddypress.org/support/topic/buddypress-2-1-bp-language/page/2/#post-200308 (section 2nd).

5th:

I don’t know, whether it is state of the art – anyway it works for me:

I insert as well my changes regarding my WordPress parent-theme as well as my changes regarding BuddyPress into my wp-content/themes/reddle-child/style.css.

Further reading:

https://codex.wordpress.org/Child_Themes#How_to_Create_a_Child_Theme

so when you say I have to activate our child theme in the Admin panel, I’ve seen this and have tried the preview and it takes over our real theme which is ClassiPress.

Parent and child theme work the following way:

If there is a style definition for e.g. h1 in the parent theme as well as in the child theme, then the style definition of the child theme for h1 is used.

Is there only a definition in the parent theme for h1, then the parent theme definition is used.

And the same regarding BuddyPress:

If you write nothing regarding #buddypress div.item-list-tabs ul li.selected a into your child theme, then the BuddyPress-definition is used; otherwise the definition, which you make in your child theme, is used.

Or saying the same thing in a more abstract way: The child theme does not substitute the entire parent theme, rather it has primacy in the case of contradictory style-definitions for the same element.

typing the code in directly finally worked!

Cool.

I added the code to the bottom of the classipress child theme, saved it, refreshed my screen and nothing happened. maybe because i used cut-paste instead of typing it in.

I guess this could be not the reason, maybe it was because the browser or server cache.