how to place a sidebar that goes horizontal above the content area

have a look into footer.php, sidebar-footer.php, and functions.php of Twenty Ten (this is for a horizontal footer sidebar, but applies equally to any ‘sidebar’ area in a theme).
or related: https://www.ads-software.com/support/topic/how-to-add-a-widgetized-footer?replies=5

you possibly need to make a new div below the header or nav div inyour theme.

for posts in three columns check for instance: my post; there are many other ways to do this.
https://codex.www.ads-software.com/Post_Thumbnails
https://codex.www.ads-software.com/Function_Reference/the_excerpt

once you decide where exactly you want to have the three columns, locate the right template to edit: https://codex.www.ads-software.com/Template_Hierarchy

Hey thanks for your reply, i will checkout the links.

Cheers