Monitor size adjustment

Good afternoon all. I went to the Goodwill and picked up a monitor with HDMI and a mouse and a keyboard four less than $10. Everything seems to work I just don’t know how to adjust the size of of everything to fit my monitor anybody have any ideas?

This should be standard Raspberry Pi configuration and is detailed here: How to change screen resolution of Raspberry Pi - Stack Overflow

Either use a keyboard and mouse and Ctrl-t Ctrl-c to get a command window or SSH in (bbmc/onefinity). Either should work.