If you don't yet have access to the Ads API, then you'll need to wait until - and if - you are granted access. There is nothing else you can do at this point.
Once you have access to the Ads API, have a look at our docs starting from this overview - there are plenty of things there to read.
It's also worth having a look at our FAQs, especially the ones listed under
Basics/General. If you are coding in Python or Ruby, we've got you covered with officially supported SDKs!
I hope this information is helpful - I am not sure exactly what your situation is with regards to the Ads API, so I tried to cover all scenarios. In any case, I believe you should be able to find all the information you are looking for in the provided links