Correct the sentences: 1-whats the name of the teacher.
2-Be sure to visit diana when you are in minnesota?

1- What's the name of the teacher?

2- Be sure to visit Diana when you are in Minnesota.

Explanation:

For 1, you need to start your sentence with a capital letter. Since the first word is a contraction, you need an apostrophe. The period is changed to a question mark because it's an interrogative sentence.

For 2, Diana is a proper noun; therefore, it should be capitalized. Minnesota is also a proper noun, so it must be capitalized as well. At the end of this sentence, since it is just declarative sentence, it requires a period at the end, though an exclamation mark might also be used. It is most probably a period though.