Mac running very slowly, freezing up

Hi,

I am really hoping you all will help me out. My Macbook started running really slowly the last couple of days. When I use the web, it is taking a very long time for the page to load and sometimes its freezing up on me. I have downloaded anything new recently and it was running fine before. I checked the hard drive and it says I have used about 218 out of 249 GB.

I dont know what the problem is but I am a distance-education student so I HAVE to get this working again very quickly. I do not know much at all about computers. Is 218 of GB a lot filled up? Or could it be something else. Also, I read something about downloading Onyx..could that help?

I really would very much appreciate some help!

Is it only when using the web? If so, have you tried another browser (as in firefox, if you've been using safari.. or chrome..etc). If it persists on both, have you tried using a public DNS (such as google's 8.8.8.8 and 8.8.4.4)?

Yes, its only when using the web. I currently use Safari..Ill try making the switch to Firefox and see if that works...