Hey guys! Brand new player, rated at around 700 on chess.com, wondering if I should study openings or endgames? Or should I just get fundamental principles and save the openings for later?

I'm pretty new to chess, shot up from a pitiful 250 about a month ago to right around 700 right now. Decided to stop playing short games (less than 5 minutes) and just do 10 and 15 minutes. Trying to just stop blundering basically. Wondering if I should also be studying openings? I know the first few moves of the English and the French defense but that's really casual knowledge.