Fizi,

Created some Banners for website but not displaying on Fitness theme, so I need to do anything special..

The theme not influence for the e107 core.
You can acive the banner menu to the menuarea on the admin page. If you want put the banner into the special place, you need modify the theme.php and insert the code

{ BANNER }

or if you give name for campaign, you can give it

{ BANNER=campaign_one }

So...the banner not the theme problem.