right so make sure you combine everyones advice here;
slowly turning up the heat (maybe 2degrees or so every few hours) gradually to around 84 or so (sorry I said 86 earlier might be too high), you don't want to fry your fish but you want to fry the ich and any potential ich in the water like whiskers said. leave the heat like this for 2 weeks or so to ensure any ich is rid of. and the salt.... using "Aquarium salt"
For salt dosage, use 1 tablespoon per 5 US gallons(if you're outside of the US, you'll need to convert that). Be sure to dissolve the salt first in a bucket or bowl with some tank water or dechlorinated water. Don't ever just dump the salt directly into the tank. For the heat, raise the temperature up to at least 82-84°F(again, you may need to convert that to Celcius). Treat for at least 3 weeks, or for at least 4-5 days after the last white spot falls off the fish. And, one other thing to remember, salt does not evaporate with the water. It's only removed via water changes. So, if you remove 5 gallons of water, you'll need to replace 1 tablespoon of salt. Here's a couple of good articles:
http://www.peteducation.com/article.cfm?...
http://en.wikipedia.org/wiki/Ichthyophth...
Normally meds like kissy mentioned and some others would be a fine solution too, just not for sharks/loaches, and other scale less fish that might be sensitive to it