Content Writing - document how to use a specific web app

We are creating an article website to be the online "HELP" for a new web app that is under development. This documentation has been started at [login to view URL] but is incomplete. The job is MORE than a re-writing a few product pages. The idea is to describe the various product features using TEXT and IMAGES (screenshots), how they work and the results produced. Usually, one doc page per feature. We also want to use LINKS inside the content so visitors can click and view a live example in a separate window, if they choose. The slide-out menu acts as an "outline" to the web app and provides the big picture. Several pages have been started, many are duplicates/placeholders to be updated. New pages will be created as needed. In particular, the VIZdex DOCUMENTATION section will be expanded with text narrative of how each function works as well as screenshots, when helpful. All examples will be taken from [login to view URL] and you will look there to see and learn the web app features to be documented. I care very much about the "VOICE" of your writing as well as your ability to articulate in words what you see on the example screens. Spelling is important. I do not mind paying a bit more for quality work. Even though it should be TECHNICALLY accurate, I want the site to have a FRIENDLY, CONVERSATIONAL tone. We are looking for you to 1. help us improve the site with some initial chunk of hours - bid whatever YOU think is reasonable to start off 2. demonstrate the ability to deliver GOOD work 3. be available for just a few hours on a regular basis as the software changes and we need updates to the documentation site Thanks for your time and consideration.