Those of you that have used electronic duster before...help?

I have been having several problem with my laptop and everytime I look up the issue or tell someone about my issue I keep getting that it sounds like my computer is overheating due to dust build up. So I went and bought multi purpose duster for electronics and I am reading the warnings and it is starting to scare me. I am afraid to use it on my computer even though that is the purpose, I know! What can I use it on? Can I use it on my ports and in my cd tray? Is it normal for the can to freeze your hand? Is it normal for it spray some kind of white substance all of the surface? Maybe I am thinking to hard about this, but I just don’t want to mess up my laptop more than it already is. If anyone can tell me how to properly use the duster I would appreciate it!

Ps: I read the entire can and it is not specifying what I can use it on. Thanks!