I have a script on my computer, how to import it to the device via USB?

Use iTools (or any desktop assistant that can connect to iOS devices) to copy the script file to this directory on the device:

<user system>/1ferver/lua/scripts/

Note: <user system> is just the display name of the device's user filesystem in iTools. Different assistants may display different names, such as User System or File System (User).