The first if you want to change url of link you can go to admin cp/ menu /
Choose menu which you want to change and click to view details. In details form you will see button change type. Click there and go to Extenal link and now you can change the url of its.
The secord, i don’t know what is menu you talking about but if you want create one more like its. Example i have home in mainmenu and i want create a home menu in top menu. Both of them linked to frontpage i can create home menu in mainmenu then i create a home menu in top menu ( with type is alias ).
Goodluck
