Help with correcting CSS code

Hello

I am not a seasoned CSS programmer and need to be careful about not making errors on my WordPress site, as this can cause the site to shut down.

I am in the process of following the instructions at https://www.designwall.com/guide/dw-...s-integration/ for integration of the plugin BuddyPress with the plugin DW Question & Answer. When I copy-paste the recommended code

include_once get_template_directory().’/buddypress/bp-custom.php’;

into the correct area, multiple errors are reported as follows:

Expected LBRACE at line 5, col 14
Unexpected token ‘get-template_directory(‘ at line 5, col. 14.
Unexpected token ‘)’ at line 5, col 37.
Expected INDENT at line 5, col. 39.
I am in turn advised of the following:

There are 4 errors which must be fixed before you can save.

Update anyway, even though it might break your site?

I would be grateful for help with correcting the line of code I have provided.

Many thanks!