I can see you do not have a negative voltage so: see attached file.
You must choose the correct op-amp. Most op-amps will not work with their inputs near the same voltage as the supply pins. ( If the power supply is 0 to 12 volts then many will not work if either input is less then 2 volts or more than 10 volts.) You need to look for an op-amp that has a “common mode input voltage” that includes the negative supply. There are some amps like that, you might start out looking at MicroChip for low voltage op-amps.