For communication between the PC and the Arduino have a look at the examples in Serial Input Basics - simple reliable ways to receive data. There is also a parse example to illustrate how to extract numbers from the received text.
The technique in the 3rd example will be the most reliable. It is what I use,
You can send data in a compatible format with code like this (or the equivalent in the PC programming language).
Serial.print('<'); // start marker
Serial.print(','); // comma separator
Serial.println('>'); // end marker
I use the Python Bottle web framework to create a simple web server on my PC.
And the code in this Python - Arduino demo is essentially the same as I use for communication with the Arduino. It is very similar to Serial Input Basics which was written more recently.
If the browser will not be making calls to the server as a result off user interaction then you can arrange for it to call the server at regular intervals to get the latest data. The w3schools website has a huge amount of tutorials on everything to do with web programming.