depends where you want to move next step or the line of code that will process the transaction
for example i you want to to fill application and waant to save and move next page ..... the code will do this transaction you lace it in a IF statement like below
If Page.IsValid Then
save to DB
OR
transfer page
etc.........
ENDIF
and if the page is not valid you can exit the sub or do nothing ..... i hope that helps!!