So basically, You want a report to show how many incidents were opened on a specified day?
You need to think how you want the data.
Do you want a parameter in the report so you can choose a specific date?
Do you want the report to be automated, so each morning you get an email with YESTERDAYS report?
either way should be fairly easy.
I will let someone else comment on the best way to do that,
but personally, I would simply do a select expert formula along the lines of:
{probsummary.opentime} = date(currentdate)-1
this will show all incidents opened yesterday.
same for parameters..
{probsummary.opentime} = {?dateparameter}