Acer Aspire AM3450 Desktop Computer.
You have a very old computer with a very old AMD GPU HD6xxx card from the specs I read about your computer.
If you can afford it, I would just purchase a new computer rather than upgrade the processor. The processor will probably cost more then the computer you have.
BUT:
If you can't afford a new computer than you need to download a free program called SPECCY. That program will show the Make & Model of the motherboard your computer has installed and other hardware and software.
IF the motherboard is not some ACER OEM motherboard but has a common Motherboard from one of the manufacturer's like MSI, Gigabyte, Asus, ASRock, etc then once you know the Make & Model of the Motherboard you can go to the Motherboard Manufacturer's Support site and see what Processors are compatible with WHICH BIOS VERSION!.
Otherwise you going to have to open a ACER SUPPORT ticket and ask them what processors are compatible with the computer model you have.