If you are using adsense, first log in to your adsense account. Go to adsense setup at the top of the page. Select the type of ad you would like to use (probably adsense for content). Select the type of ad features you would like such as the size and color and what not in the next few pages. Once this is finished, click Submit and Get Code. Copy this adsense code and place it in your website where you would like the ad to display. I hope this helps
There are many advertisement media websites which allow you to earn money through your website. All you need to do is to create an account on websites like Google adsense or Smowtion advertisement network Once you site is approved by these companies, you are then allowed to generate a code by logging into your account on any of above mentioned websites. You don't need to do anything beyond your knowledge. Once code is generated for you, copy that code and paste in your website or on that place where you want ad to display. Thats it, you are done. Both of the websites which i've mentioned above are the best and you can have ads of both websites on same page. For any other query PM me