help to write API Code

Greeting,

Never use API for programming, so if some one can give me some idea ( like ABC or 123 very basic idea), will be very help.

for example, I want to Get API Versions

          This API enables you to query for all the API versions supported by the vCenter Chargeback Manager setup.

          Syntax

          The syntax for calling this method is:

          GET <Base URL>/apiVersions

          A sample API call is as follows:

          GET https://123.123.123.123/vCenter-CB/api/apiVersions

          User Privilege

          To call this API, you should be authenticated but do not need any special privileges.

Create the code, then save it as ...

then what?

any thank you very much, any information will be very helpful.

Thanks

Newbie