Here Is the thing my instrctor is accusing me of pligrism and i dont know what shopuld and should not to do to?

ok the thing is on the last paper i did i used online sources and book then i tried to cite my sources .so the instructor told me i did pligrism and i need to meet with her some time this week .I never cheat and i have very good grades .this accusation could ruin everything i got and i am really worried about it as this could hurt my achademics record.i tried to be carefull abot my cition nad everything what should i do ?