First, pelvic floor exercises have nothing whatever to do with sitting on your floor while doing them.  The floor referred to is the floor of the pelvis and the muscles are those stretching from side to side across it, attached to the pubic bone at the front and to the spine at the other.
These exercises have long been know and practised by women to strengthen their vaginal muscles and prevent the accidental loss of urine.  Only recently has it been realised that the exercises are beneficial to men in much the same way but with the added bonus of helping erectile dysfunction.*

Perhaps the best way to identify these muscles is to begin to urinate then, mid-stream STOP. Hold it for a couple of seconds and restart.  Do it again to make sure. Those are the muscles!

Once you are happy you know where they are you can begin the exercises in this way:
Tighten the muscles around the urethra and anus, lifting the muscles up inside.
Keep this tension for about six seconds and relax.
Wait for about ten seconds and repeat.
Do this exercise ten times.
To finish, do the above another ten times in quick succession.
That is it.

You should aim to do this set of tensions twice a day.  They can be done standing, sitting, in the car, at the bus stop, anywhere; it’s up to you.

It is possible that the effects will be seen in just a few days but if not don’t worry as generally speaking it will take some six months for you to regain full prowess.

* Dorey G Dr., University of West of England Bristol study, 2005

The results were thus:
For a survey of 55 man with an average age of 59
40% regained normal erectile function
35.5% improved
25.5% showed no difference.