Baseicly all you need to do is this edit this file with
sudo nano /etc/netplan/10-my-config.yaml

network:

  version: 2

  renderer: NetworkManager

  ethernets:

    eth0:

      dhcp4: true

      optional: true

  wifis:

    wlan0:

      dhcp4: true

      optional: true

      access-points:

        "SSID":

          password: "your password here"

          mode: ap

fill out the SSID and the password parts
note the wifi device may change use ip addr figure it out

and run this to apply

sudo netplan generate

sudo netplan apply