I'm an MX rookie and have just started making the transition from 5, I've found that if I want to fade something out or in that the "effects"panel is greyed out like it's not available.
If you’re changing the alpha you need to make a tween from one key to another and then highlight the end key. On the properties bar their is a drop down called 'color: none' change it to alpha and then adjust your opacity as desired.
it has to be a symbol and it has to be on a seperate layer i think, just click on the object, convert to symbol, and then select it and you should be able to do alpha
just click on the object, when the timeline is over the keyframe and the properties bar will change. to colour:none.... change it to alpha see .jpg attached