The MID for your Delacon account can be found in several places:
The MID can be found in the top right corner of the portal view, and will be seen on every page
If you are using a super user login then the MID shown will be for the currently selected account, and will change if another account is selected.
Delacon Portal (Classic Interface)
Similar to the standard portal, the MID will be found at the top right corner of the classic portal view.
On the monthly statement, the MID will be seen under the Customer Details section on the first page of the statement.