For recreational uses: Use common sense, and take your time. No need to rush! Saying "can I use it right away" shows that you may not be ready for using it just yet.
For unplugging a toilet(known to others as the 'loo'): 1. Screw the MXL 990 onto the stand. 2. Stand back. 3. Flush. 4. With your hand affixed to your MXL 990, thrust your hand in a forward and backward motion vigorously to remove the blockage. 5. When your done, wipe the MXL 990 clean and leave out to dry.
For common audio purposes such as 'recording': Alright, first things first. Is the mic on the stand? If so, proceed. Now, connect the XLR cable to mic, and then into your interface/mixer/what-have-you (that has phantom power). Then you should be able to use it.