Here you go. Thats how you use one. Its a she-pee in the diagram above, which is a plastic reuseable version of the p-mate, which was available at VLM. It has been for the previous 2 years too.
I've been using one for a long time, having discovered them at an outdoor show some time ago. I'll admit to testing it out in the bath (and then cleaning it, obviously, though urine is sterile) The p-mate is made of cardboard and you tuck the top section underneath you and the wee flows out through the funnel. You do have to tilt your pelvis to ensure it flows the right way. And not pee too fast...
Its actually brilliant when you are wearing lycra. You can pull down the front, pop under the funnel and wee without revealing anything, other than to a hedge.
Its not for everyone, I'll admit. My sister is scarred for life after the woman at the urinal backing up to her got hers the wrong way round (trousers round ankles for peeing too, most entertaining!) and wee'd on lil sis' shoes. I did laugh.