Downloading a webcam? - you mean downloading software for it? - Don't you have a CD with the software on?.
"It says it's in use but it's not" - What says what's in use?
"I tried downloading acrobat, but it won't!" - Why won't it - what error messages do you get? - what EXACTLY happens?
You'll have to describe it more clearly if anyone is to help - we can't see what you can see, and know nothing at all about your system. Help us help you.