Download
Windows: SageMath 9.3 (2021)
Mac: SageMath (choose the correct version and .dmg file)
Jupyter Notebook
To edit SageMath/Python codes, you need an editor called Jupyter Notebook.
Download Anaconda and then Jupyter Notebook: click here
To start Jupyter Notebook, type !sage -n jupyter on Windows command line and jupyter notebook on Mac terminal.
Start a project
In Jupyter Notebook click on NEW to start a new worksheet. Choose sws extension (if available) for SageMath especially if you want to work in graph theory.
Subject tutorials
Quickstart Tutorials for various subjects
Graph theory (comprehensive)
Sage tutorial
You can do a lot of cool things such as creating latex codes for mathematical expressions (matrices etc).
click here