If your theme layout is not what you want, you can either edit its PHP code to customize it (if you know some PHP) or get a different theme.

I suppose you could contact the theme author and ask them to create another version, but they may not want to or it could be too expensive.

Themes control the layout, not plugins. That said, there are some plugins that do sliders, modify sidebars and such, so there is a small chance you might find a useful plugin.

If you know a little bit of code and are good at copy/paste... you can add a "widget area" to any theme template, anywhere.

I would recommend just finding a theme that matches what you want. There are an endless supply of themes for wordpress. Put a little time in and you should be able to find the exact theme you are looking for.

Just find a theme that has three columns, there are thousands of them, including the TwentyFourteen default theme that ships with WordPress.

There are such layout plugins such as Site Layout Customizer , Post Layout , Page Layout builder. I hope that will help. Thanks !

may be I can help you. Add me to your skype: themubeen

To do this you need to some about php. If you have knowledg about php then goto function.php and search register_sidebar in this page. Here I share a link with you Function Reference/register sidebar « WordPress Codex. Read it and follow this method to show widgets.