From reading 'Ask And It Is Given' detachment/non attachment come when you are truly happy in the place you are with or without the thing/person situation you are choosing to manifest. You know that you are a complete being, with NOTHING missing. Your joy does not depend on getting the person/thing etc. So many of us, including me (Oh my goodness, I've really had to work on this, but just in the last few days things are starting to click!! ) think that we won't be happy unless we have XYZ, but it is this feeling that is blocking you from having it!!!
Once you get to the place where you love yourself and your life just the way it is, you are in the perfect place to say... "Yeah I would love to have this experience or that experience" your happiness doesn't depend on it but you know you would enjoy it.
Hope this helps!!