how to change resolution/game window size?

i have been in the settings and have switched everything to high but cant find where i change the game window size. right now its just the smallish rectangle and kinda makes it hard to read the writing.

is there a way to change this?? or will it change automatically once i actually get into game?

You can only do "Virtual windowed" mode for a full screen border less screen. Need to do it on the client before starting the game.