How to configure the word press development environment locally?

As I am new to word press, I couldnt find how to begin with. Some third party developers they created the sites and gave to them for ongoing site maintenance such as editing post, adding new post etc. They gave a just word press admin account. While I am logging to my account, there itself shows the lot of options to add/modify the page/post. Can you please tell me how to set the local development environment for my site and publish to the live.

Can we do all the changes by using online word press admin account itself or is there any limitation by doing in online?

Thanks in advance.