Looking for developer help for Invoicing application

I am working on an application for tracking some physical therapy bills. It needs to create an invoice to an insurance company that is broken down by patient and searches across a date range.

I am stuck on creating a query that can have 4 parameters, Start Date, End Date, Insurance Company and Patient Name. All of these items must be changable on-the-fly.

I built the date range filter but the application needs to be edited in order to adjust the date ranges. Now that I found out from the user I also need to filter by patient I am stuck.

I want to hire a developer to help me but I don't know how to do it. I am a developer in Zoho but I have no idea what I am doing. Any ideas?

Thanks!