Increasing the row or page size

What exactly are you trying to achieve? Increasing the size of a page is not possible in SQL Server, they are always 8KB. Increasing the size of a row is as simple as adding a column to the table definition. Rows cannot span multiple pages, so if that is what you are looking for you will need to describe your needs in more detail.
Increasing the size of a data file is done with ALTER DATABASE. Something like this:
USE master
GO
ALTER DATABASE dbname
MODIFY FILE (NAME = filename, SIZE = newsize)
GO