LaTeX is a document typesetting system that can produce attractive articles, books, and slides. It is especially useful when writing documents that have a lot of mathematical notation.
The Notre Dame Graduate School provides resources and formatting requirements for dissertations.
There is a LaTeX style package to assist with formatting dissertations conforming to university requirements.
First, either install a TeX distribution or choose an online system to use, such as Overleaf (formerly ShareLaTeX). If you choose Overleaf, be aware that Notre Dame has a site license for it, so use your ND email address to sign up.
If you choose to install a TeX distribution, the exact one will vary based on your operating system. For Windows, look at MiKTeX. For Macs, consider MacTeX. Linux users should install whatever is available through your package manager (it will probably be a variant of TeX Live.
Second, try a LaTeX tutorial. There are many on the web. There is also a handout used for the Introduction to LaTeX workshops offered at Notre Dame.
The Wikibook on LaTeX is a particularly good online reference.
If you would like a hands-on introduction, Introduction to LaTeX workshops are offered a few times each year in the Hesburgh Libraries' Center for Digital Scholarship.
Notre Dame hosted the worldwide TeX Users Group meeting in 2009. Yes, there is an international TeX Users Group!
The Center for Digital Scholarship offers workshops for those who are completely new to LaTeX. They start at the very beginning and go through adding text, special symbols of LaTeX, and basic formatting. The goal is to learn enough so that participants can find and make sense of tutorials and examples found online.
The workshops are a great way to get started, especially if you prefer to learn by doing.
The handout used in the workshop is also available. Feel free to use it as a reference or to work through it on your own.