Tutorial for creating pages with ajax
As far as I know - If you dont need any specific action to be done on the form which you have created before you hit the submit button then you should be alright 

For example: 
If you enter a Postcode on the form and you need to populate address line of the postcode before submission then you need to write AJAX to fetch the records from Database

Links for civicrm Ajax: references 

https://forum.civicrm.org/index.php?topic=28148.0

https://wiki.civicrm.org/confluence/display/CRMDOC/Ajax+Pages+and+Forms

Also you can find a good example of Ajax used in the below extension 

https://civicrm.org/extensions/civicrm-postcode-lookup

I guess this helps !!!