I amMy name is Budi. My name is Budi.

I amHi! My name is Budi. Hi! My name is Budi.

I amHello, my name is Budi. Hello, my name is Budi.

I amMy name is Budi. My name is Budi.

This is grammatically correct, but not a typical way for an English speaker to introduce their name. It is unusually formal. These days, "I am" is typically used to convey a statement of condition. "I am cold", "I am a manager", etc. To share your name, it sounds more natural to say something like "My name is Budi" or even "Hello, I'm Budi".

This pen belongs to me. If you want to borrow it, please let me know. This pen belongs to me. If you want to borrow it, please let me know.

If you want to borrow it, please let me know.

Good, but this pronoun ("it") is a reference to the "pen" mentioned on the previous line. You should place "If you want to borrow it, please let me know." on the same line as "This pen belongs to me."