I have just begun to learn and my serve isn't very good.
我剛剛開始學習,發球不太好。
We shall never have friends if we expect to find them without fault.
指望朋友無缺點,永遠休想交朋友。
I am sorry that you have a disagreement with your father. Personally, I think it is important to follow your interests and your abilities, and it sounds as though you have plenty of both of these already.