Nothing is "urgent" here, and it's damn rude to say so. People here are volunteers with their own jobs to do, and help others as and when they can, and there is no priority to who's question gets answered first (so you are also being rude to all the other people asking questions who, no doubt, would also like a quick answer).
Please read: Re: 2. How do I ask a question on the forums?
Your question is too vague, and you've provided no details about what you're really trying to achieve.
e.g. what has populated the data in the collection? if it's come from querying the database, why put it in a collection in the first place?
Associative arrays are collections of data, cursors (ref cursors and all others) are not collections of data, they are executable programs used to fetch data. You cannot put a collection of data into an executable program, they're not the same concept.
There are ways to make a collection appear like a table so that you can query against them, though this is often not performant (they don't have indexes like database tables which are specifically designed for querying against). For example, you could use a pipelined function, or you could use the TABLE function, if the collection supports it in your particular situation. However you say it's an associative array, which is a PL collection type, not an SQL collection type, so your likely to going to need a pipelined function for that (unless you've got a 12c database - but you didn't bother to tell us your version).
Post more relevant details and people may be able to help you, when they have time.