Unless you work in a field such as law, most commonly the word you're looking for is "uninterested." "Uninterested" simply means not interested: I am uninterested in fishing.

"Disinterested" means impartial. A disinterested person has no personal stake in taking a stand on the issue. For example, judges must be disinterested in the cases they try.

Some style guides indicate that the use of "disinterested" in the place of "uninterested" is gaining steam, but if you don't want to anger the purists, use "uninterested" when you mean not interested.