A few things... First, gas rises. If you can manage a headstand where you balance your body against a wall, with someone spotting or helping you, the gas will head right to your rectum and make it out of your anus faster. No kidding. My little sister used to do this thing when she was gassy (she has a spastic colon, too). She called it The Fart Position, as if it were yoga.
As to the rest of it, really try to evacuate your bowels as soon as you can, even if you have to use an enema (though that didn't work for me). Your stool is rock hard and will grow huge because you're not eating raw or cooked veggies, or anything with enough fiber to move your bowels. Short of doing the enema, try stool-softening suppositories (they didn't do much for me, though).
The two most important things, though, are 1) drink a fiber laxative right away. A tablespoon of metamucil in a few ounces of water (so you can get it down faster and not have to deal with the nasty jelly), 2) followed by a glass of water you sip over about 30 minutes, will soon find its way into your intestines. The fluid softens the stool and the fiber creates a slimy, slick surface area so the stool can get out pretty quickly.
Don't allow your stool to back up or become constipated. This is a horrible thing to happen when you still have a surgical belly. I don't know why my doctor never told me about this before surgery. I had the worst constipation and it was something I knew nothing about because I'd never been constipated in my life. I could not move this Prest-O-Log ouf of my bowel for 24 hours and I visited the toilet at least 20 times. It was agony and very bad for my RYGB. I had weak pelvic floor muscles and of course, a bad diet that was now a liquid diet, so I was screwed.
Take a fiber laxative.
Drink your 8 glasses of water.
Don't push or strain during a bowel movement.
If things won't move over 24 hours, go to the ER and have them disimpact you. Bowel impaction is very bad for your body and can actually cause damage, especially after weight-loss surgery. It's extremely serious.
You can drink a fiber laxative several times a day if need be, but my routine after my baptism by fire was a tablespoon at bedtime in 3 or 4 ounces of water, mixed quickly together and swallowed as quickly as possible. Then I added more water by drinking as much I could and went to bed so the liquid could find its way to my stool and soften it overnight. Worked like a charm.
If you search the old posts, you'll find it's pretty common for our members to experience either constipation or diarrhea post-operatively. For many, it becomes chronic. If that happens to you, use the best, most natural tools available to you in order to balance the flora of your intestines.