How to add rows dynamically to the existing form

I want a small clarification : can anyone help me out with this?
Iam designing a page , which will contain rows . I cannot have about 100 rows on the page as it is very clumsy to look at.
so, I want the page to contain 10 rows. If the user wants to add more, he must be able to do so.
Can I have a scroll bar ? or
Can I have an option put up which would allow the user to add more rows. and also, if the user does not enter data after adding a row,
will that row be deleted ?
What are the required validations ?