5k = 3.1 miles. Start slow and push through the first mile, it will get better. Your breathing will even out and your body will stop wanting you to stop. You can stop and walk but try not to until after the 1st mile and try to keep the walking to only a few seconds.
Best why to train is the run everyday. There is an app called couch to 5k, you can get it and follow the directions. Or go out when the sidewalks get cleared and run to a point you set prior to starting and back. Do that for 2-3 days and continue to move the point. I ran my first 5k without training in 35mins.