This YouTube video shows a good technique for dealing with flat tires. It shows the back wheel as an example, which is good because there’s a couple more steps involved in changing a tire on the back versus the front.
If you’re not familiar with flat tire changing, watch the video and you’ll see how easy it is if you follow the right steps. I disagree with one portion of the video, though. It advises putting your tire back on using tire levers. More often than not, this is going to cause a pinch flat. You’re better off to get the tire on “by hand.” This can be difficult with some tires, but it is worth the extra time and effort.
Working without levers may require that you stretch the tire a bit in order to get the last part of the bead over the rim. To do that, place both hands on the side of the wheel closest to you and pull on the tire in both directions all the way around the rim as you slide your hands around to the far end. Then use your thumbs to wrestle the bead into place.