Code Academy Python tutorial. Codeacademy.com is a great place to dive in to learning programming languages. Sage is written in Python. So its a great idea to work through the Python tutorial.
House of Graphs, is a place to go to find information about a specific graph or class of graphs, and to add graphs that might be of interest to others.
Grinvin is a
free computer program that can be used to calculate invariants, generate graphs, and otherwise explore.