Paul writes to the churches in Galatia out of deep concern that they are forsaking the gospel that he has preached and are listening instead to the message of certain Jewish evangelists who are arguing that Gentiles must be circumcised according to Jewish law before they can follow Christ. Paul, himself a Jew, insists that people are justified by faith in Christ rather than by keeping the requirements of Torah. By faith, they participate in the death and resurrection of Christ and now live as God’s children and heirs of God’s promises. By the Spirit’s leading, this life of faith is no longer marked by sinful works of the flesh but bears fruit in freedom that serves the neighbor through love. -James Boyce  on Enter the Bible

Galatians contains 6 chapters.  You can break them up however works best for you. This is the recommended break down: 

Books about Galatians
Galatians (N. T. Wright for Everyone) by N.T. Wright. Published by IVP Connect.

Galatians in The New Interpreter's Bible: A Commentary in Twelve Volumes Volume XII by Richard B. Hays. Published by Abingdon Press.

Books about the New Testament
The New Testament: A Very Short Introduction by Luke Timothy Johnson. Published by Oxford Press.

The Writings of the New Testament: An Interpretation by Luke Timothy Johnson. Published by Fortress Press.

Books about the Bible
Making Sense of the Bible, Rediscovering the Power of Scripture Today by Adam Hamilton. Published by HarperOne.

What Is the Bible and Who Is It For? A Book for Beginners, Skeptics, and Seekers by Emanuel Cleaver III. Published by Wesley's Foundery Books.

Enter the Bible resource
Enter the Bible is an excellent, free resource out of Luther Seminary.
It is a website designed to help everyday disciples and spiritual seekers engage Scripture in ways that are thoughtful, accessible, and faithful—with an aim to encourage and strengthen faith in the God revealed in the Old and New Testaments.

Each book of the Bible has its own course.
There are timelines, maps, videos, a glossary, and so much more.

This is a course on the Absorb Platform, which is a website utilized by the Missouri Annual Conference of The United Methodist Church for education.

This course introduces the basic principles of biblical interpretation. You'll explore how the Bible came together, methods for interpreting scripture, and helpful tools for biblical interpretation.

It is taught by Mark Statler, a lifelong Missouri Methodist. He currently serves as the Director for Leadership Excellence in the Missouri Conference Office.