check availability by date

i have a problem to create a booking page. i currently develop a lend/borrow hardware system. my friend want me to include a list of items that still available and not been borrowed yet based on date chosen before user want to continue booking( ex: hotel reservation 'check availability'). i already try based on any reference that i found, seem it doesn't work at all and i'm confused.most of the reference are focus on database, but how about the form and others.i really need somebody to help with a simple coding and easy to understand. tq