How to upgrade Processor, MHz and RAM

I am attempting to install a work-at-home program to receive calls and process orders from customers but the installation process called WAHA Assistant Computer check has informed me the my current as it is currently (Intel Celeron Processor – 486MHZ – 95 96 MB of RAM,) should be AMD, Intel Celeron, Pentium III or 4 800 MHz – 256 MB of RAM. My question is how do I upgrade my computer to support this system? Thank you in advance for your immediate response.