VPN on mikrotik server

hello every body

I have ADSL router with ip 192.168.1.1 and its connected to Mikrotik routerboard with ip (192.168.88.1), I would like to make VPN server on the routerboard and use the vpn from outside the network (on the internet ) what is the steps and do I need to forward a port ? if yes how to forward ?

n.b: I have dyndns account to add on mikrotik if this would be included i don’t know

thanks very much

Filter
Make new filter:
GENERAL:
Chain: input
Protocol - 6 (tcp)
Dst. port - 1723
ACTION:
Action - accept.

Enable PPTP server on PPP.
Add Secrets with local and remote address (e.g. 10.0.1.1 for local and 10.0.1.2 for remote)
Use in default-encryption profile your internal DNS server (think 192.168.88.1)

Do not forget to remap port on ADSL router to mikrotik routerboard IP (port 1723)