hello I have been able to create a portal to another map but when I type the command /mvp modify dest PORTALNAME
it says it can't find the portal
but I can select the portal and modify it no problem.

/mvp modify dest p:

You can look at this https://github.com/Multiverse/Multiverse-Core/wiki/Basics-(Portals)#make-it-go-somewhere and this https://github.com/Multiverse/Multiverse-Core/wiki/Destinations