Im kinda lost in the game

I am in rank 5, just reached netune but a guy kinda rushed me in there, i played for a while with a lot of big pauses and at this point i dont even know wich one is the main questline, i dont know where to go or what to do in the game, i dont know if i should be looking for prime weapons and warframes? I didnt get much of the lore until now neither had any need to improve my frames, what am i missing?