Show Ads at Left and Right Inargin on main and every page of WordPress Blog

Hi,

I want to show the ads at the left and right inmargins of size 120×600. Can anyone help where to put the ad code or any plugin which will help to show the ad at that places.

See the image in link below for clarification.

https://www.infozonepk.com/wp-content/uploads/2014/12/Left-Right-Inmargin-Ads.jpg

Thanks,

Asif