Init Form scripting

I gave an initiation form on a workflow to pass parameters WFInitForm.aspx

I can't find where this is on the site.

Given the form:

Name1:

Level 1 (dropdown box nbrs 1 - 6)

Name2:

Level 2 (dropdown box nbrs 1 - 6)

Name3:

Level 3 (dropdown box nbrs 1 - 6)

When someone clicks on the Level to select the value, I want to operate on the next Level to insure it is equal or "plus 1".  If it is otherwise pop up an alert.

Can I edit this form?  How would I address these elements?

Thanks

Tom