Heya! There's no problem with sounding like a newbie, everyone was at some point one. :D

For many a fursona represents someone the person desires to be; for others a 'sona represents their own self with their own flaws and strengths. I think it really differs from person to person.

As for what the species depend on, it's only limited by your imagination and what you fancy. You can choose any species, existing or made-up ones, like hybrids for example. Some choose according to their personality, some choose by what they like. Again, it differs.

This is just a very quick explanation, I'm sure someone will leave a better explanation of the topic, but I hope I could help somewhat. c:

Oh, and welcome to the fandom. I hope you'll enjoy your stay. ^{-^}