Hi, giorgio.
That process was discussed on some length in this thread, which is why the search for DME update (not alignment) gave me quite some returns.
Maybe you just jump into the linked posts and then explain which step is the most unknown/unclear one, ok?
Be aware that the docs in the Civa folder also include a tutorial which explains the single and the dual DME update in its chapters 6 and 7.
I hope this all doesn't sound too rude, but it's difficult to go through already discussed items again and again, so I just point to the 'it's already there' fact.  :)

And here are the search results. Mainly start reading at page 10 of this thread to see how Sanal and Mark went through the updating process if you like.
And you are definitely not stupid to struggle there, the thing is a somehow cryptic and tricky one, no doubts.  :)