Still quite new at all this, I tested at MyHeritage and have the rawDNA data.
I used GEDmatch, and some other site that said it could find my haplogroup or something via the DNA data that I had.

Now I see people use all kinds of calculators, showing them how "Slavic" they are or how "Celtic" they are etc. How much is from the Baltics and how much is from Balkans, what time era they came there etc etc...

How do people do this? I tried looking for an explenation, but it's all very confusing or very short answers.

I see people post long strips of code around the forums, what is that and how do they get it? What kind of ways can I use my own PC to calculate stuff? How long does it take?
I also saw this program called Admixture Studio, which looks pretty good but I couldn't get it to work I think. I tried different calculators and get the exact same result, with Oceania being the largest. But im pretty sure it's wrong, it's the same percentages and wrong places for me every time.

So if anyone would like to please help me a bit?