with grinding, usually the girl does most of the work. You just sit back and enjoy it. Most girls in high school around your age though aren't that good at grinding, so don't expect it to be all that great. If you get pretty good at dancing, you can do body waves and other neat things while the girl is grinding on you, making her more interested, but I wouldn't be too caught up in it.
with regular slow dancing, you grab the girl right above the hips (its easy to know where to hold her if she isn't fat and she has the hourglass shape, its where she gets skinny above the hips). She'll usually put her hands on your shoulders.
Proximity will be your biggest issue when you slow dance. Heres the key though: HAVE CONFIDENCE!!! Don't start off slowdancing with her at arms length away (like 2+ feet) and slowly creeping closer and closer to her. Thats a TERRIBLE mistake, and you don't come off as confident, and thats a sign of weakness. Of course, your 14, she's probably around your age, so you don't have to have your bodies touching, as she'll probably feel awkward, but get fairly close.
Whenever you dance though, make sure you dance on beat! From my experience, alot of girls have a natural feeling for rhythm, and they can dance to the beat naturally. But yeah, if you don't have that natural feel to the beat of the song, just count out the rhythm in your head.
concerning ur date, don't dance with her every song. Many guys come off as desparate when they are asking their date to dance with them at every slow song or grind with them at every fast song. Scout out other prey, dance with other girls....but make sure to dance with your date too!
Good luck
