Try the Add Post URL plugin by Easwy Yang. You can add banner ads at the beginning or end of your posts.

thanks , but i don't need plugins i need to add ads code in style manually

If you prefer to add your text ads and banners ads manually, copy the bits of code below to a text file (like notepad) so you can edit them.
Then copy/paste the final code to wherever you want in your posts.

Text Ad:
<a href="yourlink" target="_blank">YOUR TEXT HERE</a>

yourlink= It's the link to the page you're promoting. Paste the whole URL.

Banner ad:
<p align="center">
<a href="yourlink" target="_blank"><img src="banner-image-url" border="0" height="60" width="468"></a>
</p>

banner-image-url= It's the link to the banner image (you have to previously upload it to your site, or it has to be hosted somewhere else) Paste the whole URL.

Edit the values of Height and Width to fit the actual size of your banner.

You really should use a plugin. Whenever a theme or core files get updated, you'd have to make your changes if you put the code right in your template.
You can make a copy of single.php, page.php and index.php and pop them into a child theme and edit there. Do a search for child theme.
You can use a theme framework that has widgetized content areas, like Thesis.
You can use extra fields to include the code in your template or post.
You can paste the code right into the post under many circumstances.
There are many ways you can accomplish your goal.

its very simple open on post.php file and insert you ads

You can place them in the start of the single.php file and at the ending of it to post the ads under the title and after the article.