Questions in the comments on a blog are always great. It’s a marvellous chance to dive deeper into something. For instance: How to customize your WordPress theme.
Catherine’s question on WordPress Tips for Beginners is how to find or change a font that a theme uses.
The answer is about fonts, but almost all other elements like colour and sizes that use CSS (Cascading Style Sheets) can be changed this way. A website I consult often about CSS is w3schools. The explanation is good and there is a lot to find.