Copy 2019-07-10-raspbian-buster-lite.img to the SD card with Etcher. Then remove and reinsert the card.
Enable ssh by creating a zero length file called ssh:
touch /Volumes/boot/ssh
Create a file /Volumes/boot/wpa_supplicant.conf using your favourite plain text editor:
ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev
update_config=1
country=GB
network={
ssid="your SSID"
psk="xxxxxxxx"
key_mgmt=WPA-PSK
}