What web development niche should I cultivate?

I have no formal web training, but for the past 8 months I’ve been in charge of updating web content and uploading PDFs to my organization’s website. I use WordPress (for content) and Dreamweaver (for PDFs) to get these things done.

The site is pretty outdated, although the basic needs of our end users are served. The site has three main functions: 1) information, content and downloadable tools, 2) a search engine and PHP database to help end users find local and virtual meetings (dates, times, places, contact info), and 3) an online bookstore. Well… and 4) a third party site used by end users to make donations. And 5) a paywall for subscribers to the PDF version of our monthly magazine.

It is widely known that everything is out of date. Recently, our meeting database totally crashed, so we have a contract developer working to fix that. We also recently upgraded to a new online bookstore engine via a contract developer. Our “someday” projects are to redesign the website to make it responsive, which it is not currently, and develop a native or (more likely) web app.

What this adds up to potentially is an opportunity for me to insert myself in the chain of web people and make that my role as an employee.

If I were to aspire to that, what aspect of web development should I learn? Assuming the development would be a mix of me as more of a generalist and contractors as specialists, what should I focus on learning?

I’m happy to answer any clarifying questions. I truly don’t know what I don’t know in this scenario.