To master Buddhism could take a lifetime. There are so many traditions and practices that you could get lost in the woods without guidance.
My advice is to learn mindfulness meditation first.
I still think the best book is Seeking the Heart of Wisdom: The Path of Insight Meditation by Joseph Goldstein and Jack Kornfield. Another good introduction is Mindfulness for Beginners: Reclaiming the Present Moment and Your Life by Jon Kabat-Zinn.
If you want to get back to the Buddha’s actual teaching on meditation, you can’t do better than Satipaṭṭhāna: The Direct Path to Realization by Analayo. The Satipaṭṭhāna is available free at https://suttacentral.net/mn10/en/sujato.
For Buddhism in general, I recommend reading The Dhammapada: The Buddha’s Path of Wisdom translated by Ācāriya Buddharakkhita. This is the most popular Buddhist scripture. There are versions online.
One last note. You need to know that the Theravada branch of Buddhism is the closest to the teaching of the historical Buddha. Mahayana Buddhism originated long after the Buddha’s death. Let’s just say it changed some things.