Help on connecting kentico website with third party API

If you're integrating it with a web service then simply add that reference in your project as you normally would with a standard asp.net website. If you only have DLL references, add those references to your project as you normally would with a standard asp.net website. Then start writing code to utilize those API calls and perform actions as needed on your site.

There are many global events you can take advantage of. Also, just because you are integrating your Kentico site with 1 or many 3rd party tools, you can still take advantage of the Portal Mode of development vs. the others.

is there any tutorial in kentico regarding this

Adding web service references and dll references are standard asp.net programming. Nothing special or different using it within Kentico.

Right click the website and Add either a Reference and navigate to the dll or a Service Reference and add the web service.

How you interact with it after that is related to how you work in Kentico. For instance, if you want to call a 3rd party service every time someone updates a User, you'd check out the Global Events document I linked to earlier and use the Global System Object event <name>Info.TYPEINFO.Events (UserInfo.TYPEINFO.Events.Update) to capture the updating of the user and then make a call to your 3rd party api to send info to it.