You must re-boot your computer, and when the first screen appears, somewhere (often lower left or top right, it will tell you which key to pres to enter the BIOS. It is often the "Delete key, but can be an alternative such as one of the "F" keys.
Press and hold that key until you see the BIOS pages on screen. You should then have an index of pages (probably a dozen or so) to choose from.
Integrated Peripherals (or similar) should be one of those pages.
You cannot use a mouse in the BIOS, so use the arrow keys to navigate to the required page and then press "Enter".
Once the page opens, you should find "USB Controller" listed somewhere, and it will be either, "Enabled" or "Disabled". The legend will probable tell you to use the "PageUp/Page Down" keys to change the setting, and then probably F10 to Exit and Save the settings.
I can't be more specific, as BIOS's do vary slightly, but read carefully and you should find and be able to save the setting you require.
Finally, you will get a little window that asks you whether you want to save your settings. Be careful of this, as normally it is set in the negative. In other words, it will not save automatically. You have to tell it to do so. This is because of the previously mentioned danger involved in changing settings you do not understand, so the manufacturers try to make it fail safe!
If all else fails and you get nervous about it, press "Escape", and you will come straight out of the page and back to the index.