Hiya and welcome to Just Answer!
Many webcams will have a focus dial, either right around the lens of the camera or somewhere on the body of the camera.
Also, if you are getting blurry pictures, it may not be that the cam is out of focus, but that the lens is dirty or smudged. Follow these steps to clean the lens:
1. Start by using a sable artist's brush or a hand-squeeze dust blower to remove dust particles from the lens. Compressed air shouldn't be used for this purpose because it can damage the lens by suddenly lowering its temperature. 2. Put a small drop of lens-cleaning fluid on the end of a piece of cloth or lens-cleaning paper. Lightly wipe the lens with the cloth or paper in a circular motion. 3. Dry the lens with a fresh piece of cloth or lens-cleaning paper. Overall Warnings: Never put lens-cleaning fluid directly on a lens.
If you're still having problems with the camera or are unable to find the focus ring, provide me with the make and model of the webcam and I'll see if I can provide you the information.