We follow the book Category Theory in Context by Emily Riehl. Many recommend this book since there are a lot of well-described examples in the book. You can find the text at https://math.jhu.edu/~eriehl/context.pdf.
The links to the chapters are as follows:
1.1 Coslice and Slice Categories
1.2 Monomorphisms and Epimorphisms
1.3 Affine Automorphisms of some Finite Fields