How quotations are punctuated depends upon whether or not they are followed by in-text citations, and what else might follow the quotations. I am going to provide you with examples of as many variations as I can think of.
First, if there is nothing following the quote, this is what you would do:
She said,"Learning how to punctuate quotations is not as difficult as I thought it would be."
I have a comma after my introductory clause. I have quotation marks around all that the person said. Because what the person said is a complete sentence within itself, it begins with a capitalized word. Finally, the period at the end of the person's statement is inside the closing quotation mark.
Next, if what the person says is not a complete sentence, this is what you need:
She said the restaurant "was not as good as I hoped."
In this instance, there is no comma before the quote or a capitalized beginning.
Next, if there is something following the quote that would ordinarily involve the use of a comma, the sentence needs to look like this:
She said the restaurant "was not so good," and this led me to change my mind about trying it.
The general rule on this is that if you need a comma to add something after, the comma should be before the closing quotation mark.
If you are using in-text citations, here is what you need to do:
One expert said,"Asian business culture is markedly different from Western business culture" (Smith, 2014, p. 75).
Notice that there is no period at all at the end of the quote. The period is placed after you close the parentheses of the in-text citation. This is true whether you are using APA style, the example above, or MLA style, in this example:
One expert said,"Asian business culture is markedly different from Western business culture" (Smith 75).
I hope this helps you with your writing!