If you want to run-walk or run-walk, all the better. Start with a moderately-paced walk, meaning you can chat comfortably with a partner. If you are breathing too hard, the pace is too fast. Slow down a little so you can talk normally. The faster you go, the harder you are breathing and the harder it is to talk. If you want to go faster, minimize the talking and shorten your stride a little, whether you are running or walking. A shorter stride, not a longer one, is much of what helps you go faster.
Then when you feel comfortable and strong enough, start to run and maintain that speed and pace as long as you can. The longer you do this, the farther you can run at the pace you want.
Then when you start to walk again for however long (5 minute run, 1 minute walk, for example), keep your stride short (running length with your feet landing as close to directly under your body as possible to maintain proper alignment) and keep your arms up and pumping as if you are still running so you can walk more efficiently.