Here are two pages from OWL at Purdue University that give definitive instructions for creating in-text citations and for endnotes and footnotes, MLA style. The third link is from Literacy Education Onlline.

For the serious student in grade 11 or 12, who wants to learn academic skills required in university papers:

In-Text Citations, or what is also known as Parenthetical Documentation

Here are three different sources for this. See which one you like the best.

MLA In-Text Citations

MLA Endnotes and Footnotes

Parenthetical Documentation