OK, so you're always going to need HTML and CSS, but Bootstrap is a saviour for those who want to be lazy with their CSS
For the front end actual programming, you're always going to be best off using a Javascript library, something like Jquery or Vue.JS. For the back end, to interact with your database, you're better off with either PHP or Python. There's lots of material to learn on the net for all of this, so you shouldn't really struggle if you've done some programming before. PHP is actually based on C based languages, so it may be an easier choice to learn, though a lot of people are preferring to use Python these days. PHP is by no means outdated, and is still being updated regularly, but Python is better at data science stuff.