$ mkdir ~/repo
$ cd ~/repo
$ mkdir incoming conf repository
$ cat > conf/options <<EOF
morguedir +o/old-versions
outdir +b/repository
EOF
$ cat > conf/distributions <<EOF
Codename: stretch
Origin: <you>
Label: <you>
Description: <description of this repository>
Architecture: source amd64 i386
Components: main
SignWith: <your gpg key ID>
EOF
$ cat > conf/incoming <<EOF
Name: incoming
IncomingDir: incoming
LogDir: logs
TempDir: /tmp
Multiple: yes
Permit: older_version unused_files
Allow: stretch
EOF

cd ~/repo
reprepro processincoming incoming