how can i create a link to a submission?

I use JotForms to help my clients complete important paperwork online... After submission there is no way for my clients to update or change any information.  If possible i would like to create a secure link to edit a submission

If you want your users / clients to be able to update their submission at a later date, yes, this can be achieved rather easily by including the Edit Link in the emails that they are receiving.

Please take a look at the following guide:

How to Let Users Update Their Form Submissions at a Later Date

Please let us know if you need further clarifications or assistance, and we will be happy to help.