Hello!
An API (Application Programming Interface) is usually a piece of software that is used to allow connections (or to connect to) between different other pieces of software (eg one website to the other, or a mobile phone app to a website etc). The way you posted this project doesn't necessarily make me think you really understand the concept, pardon me for that ... So I need to ask: do you need an API built for your software, that will allow other apps or websites (say your customers/clients) to connect to your website and get or send some data(which would be a server side part of an API)? OR do you want to connect your website to some external source of data by means of an API that that provider gives you and documents it so tht you know how to use, what to ask etc (which would be you're the client of the API) ?
Regards,
Dragos