Recently, I watched a Movie which name is "きみのなわ" at first I was confused what's the mean of it? And then I translated it which mean's "Your Name". Is きみ another word of あなた and why なまえ is written as only な. is な short form of なまえ. In which situation I can use なまえ as な and あなた as きみ。
Well I'm no teacher and certainly no expert in Japanese but i think I can help a little bit. Basically きみ is another way to say あなた which means you, as you said. But they do have different feelings to them and situations they're used in.あなた can really be used in any setting and it's very polite but きみ can come off as rude to someone because it's usually the way maybe your boss would talk to you or someone of a higher societal position and sometimes guys will talk to their girlfriends using きみ. Now for なまえ and な, as for this you typically won't hear in a conversation the usage of な it will most of the time be なまえ. The usage of な is mainly used in literature and things of that nature. Hopefully I could be of some use :).
君の名は - that's the title of the movie basically the kanji for なまえ i.e. 名前 consists of two characters one read as na and the other as mae. First one means name, and the other one means "before".
Both 名 and 名前 can mean full name, given name, a name for an animal etc. According to Wikipedia, the 名前 one started becoming popular after the Meiji restoration which happened about 150 years ago. If you stick to namae you'll be good just remember that both can mean name.
きみ is a way of saying you that's a bit less polite than あなた, but at the same time it can be used in a romantic way. Like for example you can say あなたのめ "your eyes" but you can also say きみのひとみ, which also means "your eyes" but it just sounds more romantic. It can also be used by a boss talking to his female employees. You can find a great explanation if you google, I'm sure.