Well if you wanna do web pages, ya probably gotta know some JavaScript.

If you want to learn the Condenser API I did a few tutorials on dsteem back in the day.

https://peakd.com/utopian-io/@edicted/dsteem-tutorial-lesson-6-the-power-of-blockstream

That's the last one I did but it has links to all the others.
There's also another API called SteemJS that used to be the default.

If you want to run a server Node.JS is pretty useful.

A good chunk of people use Python here as well.
@holger80 writes a wrapper called Beam that allows Python to interact with the blockchain.