How do I change the word "blog" throughout this entire theme

Hi,

The word "blog" to me sounds like an intestinal disorder. I simply don't like it.

Can I change the word "blog" into something else, like "Journal"?

I saw a post about going to the "insert CSS" option, in order to change typeface. Where is the "insert CSS" option?

Can I use it to change the word "blog" into something else?

TIA

Carl