The AdSense code is generated from within your publisher account. This is the code that you will need to add to your pages to display Google ads or a search box on your web pages. Please follow the steps below to generate your AdSense code:

Log in to your account at https://www.google.com/adsense
Visit the AdSense Setup tab
Choose your product: AdSense for content to place ads on your site, AdSense for search to add a search box to your site.
Follow the guided setup to choose a format and colours. You can also choose any additional options that may apply to
your site, including channels and alternate ads
Your code will be generated in the Your ad code window according to your selections.
Copy and paste the code into the source code of the web pages on which you want to display Google ads or an AdSense for search box. For tips on adding the code to your page, read How do I add the AdSense code to my site?.
If implemented correctly, Google ads or a search box will appear immediately. Initially, the ads that appear may be public service ads, for which you will not receive earnings. However, targeted ads will appear once our crawlers have visited your page.