Hi and welcome to the EB forum! You will do wellto read through the stickied threads, especially the New to Earthbox?... Start Here
in the Q & A section.
Earthbox gardening is very different from regular container gardening, so some assumptions need to be forgotten. Same for in-ground gardening... best to forget what you knew and just start over in the learning process.
The box may seem to be too hot, yet if you stuck your hand down into the center of the box, it would be much cooler... not to worry.