Help with "New" program, Firefox

Thank you for helping. I have learned from your wonderful wedsite that computers can become easily infected using Internet Explorer. You have suggusted using Madzilla Firefox instead. I have downloaded the program but when i attempt to open it it says server not found. I have done (i think) what the troube shooting suggustions are but to no avail it still won't run. Also when I do succussfully run the program, do I leave Internet Explorer or would you suggest that I remove it. I am quite computer illterate. I am doing the best I can!! Thanks for your patience and support.

 

I did what you said and it worked!!!! Yeah!! Thank you very much. Now do I leave internet explorer on my computer or do i remove it?