Fix a website and make some changes

Hi, I would like some changes to my site. Theres some errors appearing on the website and here are the changes I require 1) Auto stock/customers not working showing as 0 2) Diesel/petrol should be changed to fuel in units available and soldunits and the input fields should be typeable (in add a vehicle and update stock) 3) Show 'supplier' in units available and sold units and remove 'traded in' at units available and sold unitsn also in add a vehicle and update stock 4) Delete a row function record in units available and customer database 5) Add total cost price = Car cost, VRT, service, tyres,paint, So 5 new columns car cost, vrt, service, tyres, paint (both in units available and sold units) and also in add a vehicle and update stock Another column named total cost price which totals them automatically just add in units available and sold units Sell a vehicle 1) Trade in and warranty fields are incorrect Add a customer 1) How did u hear about us field and display that in the customer database I can send website link