*I just started learning these and they really confused me whats the difference between (Douzo yoroshiku) and Hajimemashite.
hajimemashite is used when you meet someone for the first time. It's usually translated as 'nice to meet you'. Here's a video (second one) with cute examples: https://www.erin.jpf.go.jp/jp/lesson/01/key-phrases/ By the way: hajimeru means 'to start/begin'. This could help you remember that you use hajimemashite when you meet someone for the first time - you're starting a new relationship.
douzo yoroshiku (onegai shimasu) could be translated somewhat (but not exactly) as 'I am counting on you in the future', or 'please be nice to me'. Rather than just saying that it's nice to meet this person, you're expressing that you hope you'll get along well. You can also use this expression when you're asking for a favor.
Hope this is clear and helpful! Good luck with your Japanese studies.