It's pretty self explanatory, you walk and you meditate. There's not much more to it. Unfortunately, I only read German books on the topic, so I can't really send you a like, but searching the web should yield some satisfying results. In the meantime, here's what I got from my books:
1. Pick a topic to meditate about, maybe you want some insight about a certain situation or you wish to better understand a person / abstract concept. In my case, I wanted general insight, so I picked the word 'Vipassana', which means insight in Hindu. You can also pick a whole sentence, just don't make it too long.
2. Select a route. It can be anything really, you could take a stroll in the park or walk between terminals in an airport. In your case, you could walk around your office building (assuming you work an office job).
3. Walk that route, but be patient. Walk as if you have no destination in mind, be aware of every step you take. Now, don't focus your attention to much on the walking part, but try to walk 'mindfully' instead of just normal, destination driven walking.
4. While you walk, count your breath with your steps. I, for example started with 2 steps for breathing in and 3 for breathing out. But it could also be a 2 - 2 or even 5 - 3 pattern. Don't force your breath, just let it happen and try to synchronize your steps if needed.
5. Now, remember the phrase or word you picked in 1.? Repeat it to your breathing. I with my 2 -2 breathing and 'Vipassana' topic count 'Vi - Pas' for breathing in and 'Sa - Na' for breathing out. (edited)