Here you will find all the materials you need for a quick-start guide to typesetting mathematical documents using LaTeX.
Quick-start guide: A one-page explanation of what LaTeX is and how to get started by obtaining compilation software.
Template: The absolute minimum you need to adapt to get a working article in LaTeX. The videos walkthrough getting started with a similar basic document.
Exercises: A series of exercises for you to attempt during this session after watching the appropriate video. These will get you to start with the minimal template and begin to customise it, followed by a series of typesetting challenges, and practice of adding your own figures and references.
For help:Guide: A guide to all topics covered in and more, this should give you sufficient guidance to write a solid LaTeX source code. You can examine the source .tex file here. There are many other packages, commands, and to some extent everyone has their own way of coding so this is far from comprehensive documentation of LaTeX's capabilities!