Step 1:
- Connect VM instance by RDP
- Go to firewall setting
- Click advanced setting
- Click Inboud rule
- Click New Rule
- Select Port option
- Select TCP and enter Port which you want to public
- Click Next and Save that
Step 2:
- Go to google console CE
- Select setup firewall rules option
- Create an firewall rule for that Instance
- Enter Port mapping with which you want
That all!