trying to install testing from usb

I have installed Debian testing many times, many ways but not in the 
last year.

I followed some recent online instructions to put what I thought was an 
iso of testing on a stick and inserted the stick into the new laptop.

The laptop has Windows 11 with room on the SSD drive for Debian.

When I restart and select USB I get a grub prompt. I haven't figured a 
command to do the install from there.

I'm certainly allowing that I don't have what I thought on the USB stick.

TIA for any help,

Paul