The US and the UK treat punctuation and quotes slightly differently. So, I’ll do my best to explain, but either of the following are acceptable: •When using only one set of quotation marks, the single punctuation goes outside the marks— he said “oh boy” when we saw the spectacle. •This can also be written like—He said “Oh boy.” Usually, if a complete sentence is quoted, the punctuation mark goes inside the quotes. If the quote is at the end of the sentence, it can go inside or outside. (US prefers inside, UK prefers outside.
If doing a quote within a quote, alternate between double and single quotes. (US prefers double quotes first and single quotes inside, UK prefers the opposite).
I hope that helps.