What version of Firefox are you using? If you go into Firefox's preference menu you will see a Privacy tab. Click on it and you will get a section for History. In the area section just below that it will say "Firefox Will:". In the drop down box right next to it you will get a choice to Never Remember History. Select that one.
Now at the bottom there is an area that says Location Bar. Choose Nothing in the drop down box. Now when you type in the web address bar nothing should appear except for what you have just typed in there.
The Tools section that you are referring to is in the top menu section of Firefox. When you have Firefox opened just look up and find "Tools". Click on it and it will give you a drop down menu with a choice to "Clear Recent History". You need to do that in order to clean any history you currently have.