Bicycle Mechanics - taking off tire

hi ive got a puncture in my tire its on a mountain bike and ive neva took it off before with my bmx its used to be easy to take it off but i cant get my mountain bike tire off. how do i get it off ? do i have to stretch it a bit because its new or somethin ?

It depends on the tire/rim combination. Some are easier than others.

The first thing that I always do is to pinch both tire beads in toward the middle of the rim all of the way around. Then I stand the wheel in front of me with the valve stem at 3 O'clock. I grasp the tire at 3:00 and 9:00 and push downward as hard as I can. Then I slide my hands down to the 6:00 point and try to take the tire off with just my fingers. Most of the time, that's all that I need to do.

If that doesn't work, I get out some tire levers but use the same general procedure except for using a tire lever to get the bead started off of the rim. If I don't have a tire lever with me, I take the quick release out of the wheel and use that.

thanks for the quick reply im gona try that tommorow morning my tires are maxxis swampthing and my wheels are alexrims fd26

ive got it off thanks for the help i just used the tire levers a lot harder than last time not bothering about ruining the rim and its off thanks