Help with custom format

Hi there,

I need to create an audio with these requeiriments:

I know that I have to create a Custom FFmpeg export, but I’m very confused, thanks!

Set the “Project Rate” (bottom left corner of the main Audacity screen) to 8000 Hz.
Ensure that the track to be exported is one channel mono (Use “Tracks menu > Stereo Track to Mono” if necessary).
File > Export ( and select “Other uncompressed files” as the file type.
Select *8-bit" and “A-Law” in the Uncompressed Export Options