Yay!! Welcome to running! Lots of good advice has been mentioned.
I, too started with a couch to 5k app. And it worked for a while until I would have to run longer segments at a time. My problem was my pacing - I knew nothing about it. I found an app called Gipis (I think it's only available on an iPhone). This app helped tremendously. It had a training plan, and then it would tell you what pace you should be running at. If you were running too fast, it would tell you to slow down. If you were running too slow, it would tell you to speed up. This is how I learned that I was trying to run too fast for me to go the distance or time I wanted. Every time I went out to run - it was pretty much a sprint (maybe not quite, but close), and I hated it. This app helped me slow down, and when I did this is when I started to like running.

I used this app about 3 years ago, so I'm sure there are other apps out there that do the same thing or are better. Just wanted to offer something that really helped me when I first started to run. I may still not be that fast, but I enjoy it and have now ran 7 marathons and several halves.
You can do it, just start slowly and build mileage slowly so you don't get injured like others have suggested.