I run a hostel for backpackers in Sri Lanka.
The day to day work is mostly the fun stuff: talking to guests from all over the world and helping them plan their trips in the country. However I have a lot of work managing reservations, availability, and rates on the computer and keeping my accounts up to date. This is more behind the scenes that most people wouldn't know I do.
Here's the first step for high school students
Get out and explore the world after / during high school. There are so many opportunities that you can find in high school, university, and on your own time. I did an exchange in middle school plus a year abroad in university, plus I went to a boarding school in another country for my last 2 years of high school. Most hostels don't require you to have any experience to work and many places will let you volunteer your time in exchange for a free place to sleep.