It makes no difference whatsoever if the lettering is upsidedown. If this bothers you you could always extend the speaker wires so you dont have to do this.
If there are mutiple speakers then it gets a bit more complex. You need to know the impedance of each speaker, and then depending on the load you amp needs to function properly, you wire it either parallel or in series. You also need to make sure the phase is correct. Most speakers will have their positive and negative terminals clearly marked. If you don't know a simple way is to simply discinnect the speaker and place a 9 volt battery across the two speaker leads. Make note of the direction the speaker cone moves. mark the leads according to the marks on the battery. Then do the other speaker. If the speaker cone moves in, mark the speaker the opposite of the batter markings.
