Why am I having trouble with facebook not fully loading on my pc

Which browser are you using? What type of internet connection do you have? Either of these could be responsible. I'm still using a G4 running 10.4.11 and Safari 4.1.3 and stuff is not loading as fast as it used to due to the older browser. With more sites using HTML 5 older browsers seem to have a problem with them. HTML 5 was to address dynamic content, but it seems to affect static content in some cases in my experience. Loading in is one of those areas. I experience very long load in times for Facebook with my current setup. FYI, I am also using the slowest DSL available due to cost which also has an effect.

Could be your browser and/or Mac OS version. The G4s and even G5 Power PC Macs could only run operating systems up to 10.5.8. Minimum OS for running the latest versions of browsers, such as Safari and Firefox is 10.6. under the Intel chipset. Because the old browsers are slow, sites like Facebook and Google do not always support them.
OS 10.5.8 is more compatible than, let's say OS 10.4.9. Check your OS by going to About This Mac under the apple logo on the left side of the screen. It will tell you what your OS is. Your choices: Upgrade your OS to 10.5.8 or take a giant leap to an Intel Mac and run OS 10.6.8 or later. Eventually your old G4 will not be able to connect to anything because of the browser issues.