Please add the info requested in https://retropie.org.uk/forum/topic/3/read-this-first to your topic.

Please add some info about your setup and issue, as detailed in https://retropie.org.uk/forum/topic/3/read-this-first.

Are you using the RetroPie Pi3 image from retropie.org.uk/download ?

@remocscott there isn't image

@jcissell1029 after days of wasted effort, I found this:

https://forum.loverpi.com/discussion/891/retropie-how-to-get-the-current-build-to-load-emulationsation#latest

Once you've booted see the bit about EmulationStation not being found, you're dropped to a Bash prompt do:
sudo apt install rapidjson-dev
then:
sudo ~/RetroPie-Setup/retropie-setup.sh
From here you will select "Manage packages", then "Manage core packages", then "emulationstation", then "Update from source"

HOWEVER, there appears to be a syntax error as the script is named retropie_setup.sh and not
retropie-setup.sh
(Underscore, not dash)
so, to launch the script installation:
sudo ~/RetroPie-Setup/retropie_setup.sh