help: targetting a link into main section

Hi, I’m sorry if this has been discussed before; I’ve been actively looking for a solution for a few days already but I can’t find it.

I want to target a link (external) into the main area of my website ( http://www.harbec.net ). I would like to know how I can do that, for a sidebar widget and for a link in general. It seems I can target _blank _none and _top .. but what about _main ? Is there an extension I can get maybe?

Here are some the model names for my theme: (single.php) (header.php) (browsercss.php) (index.php) (page.php).

Thank you very much for you help and happy new year!

God bless,

François-Xavier Harbec