Once you know the number of cells to fill, select the top one. Use a statement like ActiveCell.value= to fill it. Then go down with a statement like ActiveCell.Offset(1,0).Select. And repeat (Loop or While) until you're ready.
This is by head. It's one of the things I'm not well in remembering, so I have to look up the details each time in the Help. But once you've got the principle, it isn't difficult at all.
Hope this helps.
Kees
I'm either missing something obvious or this is a bit of a tricky one. I want to create a macro that will automatically copy the contents of the first cell all the way down the active rows in the column. ie Column D contains values in rows 1:1456 I want to enter text in E1 and then have it copy down to E1456. What I don't want to have to do is copy and paste every time. I have to append an identical detail to several spreadsheets where the size of the 'active' portion varies greatly. I know how to calculate the number of active rows but I don't know how to auto-populate. Any suggestions gratefully received

Chowhound
Comic Vine
GameFAQs
GameSpot
Giant Bomb
TechRepublic