how to disrinct these similar words? lady . girl ..woman...female?

so worried about my Englsh~~~can you help me ? I  am a college student in shanghai,china,major in chinese. I attend a english course in another university during weekends..now I feel more and more worried because I can't  catch up with others, please give me a hand~

First notebook entry: Introducing myself I am a chinese.It is the third year of my university life,during which my life becomes busier.To learn my Chinese well,I have to read a large number of literature books,language books,and so on.No pains,no gains,I love my major and I believe I can know it deeply.During my parttime,I will play yoga,shopping,enjoy classical music,practise calligraphy,search on line…… I have a strong will to improve my English.I am weak at English grammer and I need to learn more words,the most difficult thing for me to learn English may be how to express myself better in English.For this purpose,I am here,this network,to change myself with your help.Thank you!