Hi, Roberto - I think you have it pretty close. I put my understanding in parentheses below (or marked OK if I agree with you).
-Joe Offer-


George Collins rode home to his father's door
He pulled on the bell and it rang
Rise up, mother, (to) make my bed
Rise, sister, and let me in

Come set him down, my six pretty maids
Throw open the coffin so fine
That I may kiss them clay-cold lips
Ten thousand times they have (met) mine

You go upstairs and fetch me the sheet
That's wove with the silk so fine
And hang it over George Collins's corpse
That (OK)tomorrow shall hang over mine

Now the news being carried to London town
And hung (OK) upon London's gates:
There's six pretty girls died all in one night
And all for George Collins' sake