There’s also a free program called paint.net that is very similar to photoshop and would be a great tool to practice with. I hope this helps and good luck!
Start with the basics!
1. If you have the opportunity, take classes in color, typography, layout, and adobe products.
2. Do some volunteer work, or personal projects to build out your portfolio (in addition to school projects). Use this portfolio to apply to entry level jobs. You can also use sites like Upwork to get some quick and easy jobs (though the pay is not great).
3. Talk to designers, to hear about the possibilities (there are so many things you can do with graphic design), and how they got where they are. Follow them on social media, for daily inspiration too.
4. Find out what you like, and what your style is- do you like illustration, poster/book design, web design, etc, and go after it!
Optional: start a design instagram, where you post even just little sketches, it'll help you get traction, and encourage you to keep practicing!
Am I willing to work harder than I ever have (60-80 hour work weeks) and still make less than most people who work 40?
Am I in a position where if I do not find work for a long period of time, I will not lose my home, or otherwise face great personal distress?
Do I have a fallback plan of another career path if it doesn't work out?
If I have to abandon becoming a graphic designer can I live with having to "start over"?
I'm not here to make you give up, I'm here to make sure your expectations are tempered with reality. My wife wanted to be a graphic designer. She's the hardest working person I know. She didn't make it. The warning I'm giving you is from witnessing the truth first hand. Please think long and hard about it as the decision should not be made lightly.