Name/Number Of Next Workbook In Numeric Series

I have a userform which saves its info to a spreadsheet. what i want to do is to also open a new workbook, save the same info to the new workbook, copy and paste from existing spreadsheet will do instead of linking the userform to a different workbook (i can do all this) I then want to save the workbook in a specific folder(folderA) but named by the next number ie workbooks 1, 2, 3, 4, 5, 6, 7, 8 etc exist so the next workbook should be called 9 so I need some code to look for the names of existing workbooks in the folder and determine the next. Then I want a spreadsheet to at a pre-set interval(15 minutes) open each workbook , copy the line to the next blank row and move the workbook to a second folder(folderB). The folders A & B will only contain these workbooks.