Using Zoho API V2 Without the SDK(PHP)

Using Zoho API V2 Without the SDK(PHP)

Hi, 

I'm currently experimenting with the V2 of the API, but the lack of documentation is rater harsh.
I can't find any example or 'required data / optional data' for anything (Insert record, convert Lead etc...)

Does the SDK an absolute most to use the V2 or I can use it without it.
All the example/documentation I find on the website or else is for the SDK without telling me what is needed to make the call work.

Thank you for your quick response.