Tips for building a web interface to run Python, Stata or R code?

I'm interested in creating a web interface that allows users to:

1. upload a spreadsheet
2. specify some parameters
3. click a button to run a calculation in the background
4. retrieve the output results from the calculation in spreadsheet format

I'm not familiar with web development, but I have the code to run the calculation in R, Stata and Python. However, the code is written to run after opening the spreadsheet in one of these tool, rather than in a web environment.

Where should I start in terms of developing this type of web interface? Also, is there a way to have either R, Stata or Python run calculations in the background of a web interface?

Thanks!