Building your own world,part 1

So today I'm gonna tell you about the world we've started to construct for the next campaign I'm going to run. We means me and Mathew - wonderful 12 y.o. with vivid imagination, 3 yrs of DnD and a own WoW RP-guild under his belt.
When he stated he wants to run his own game in school, we decided that this time we'll make it serious and use all the wonderful technincs we've found in the Internets.
We've spent sometime thinking if we start big or start small and decided to have kinda hybrid approach - we'll create the world to know the general location of everything, but details will be filled during actual campaigns.
After googling worldbuilding I've found wonderful 30 Days of WorldBuilding guide byStephanie Bryant and thoght it'd be cool to try it out.
And so we've started to do it together.
First day theme was called Climat and Variety and we were to determing climats and geographic places which "click" with us. The author told us to write 'em down in the notebook, but we, being computer geeks and nature lovers decided not to waste paper and just find and save some wow-pictures from the Net. So these are 8 pics that were chosen to represent key location of our world:

So here are the basic names of those places and moods we decided to give them in the order of the pictures above:

1. The Barrens - yes we play a lot :). Mathew felt danger here and I though this place to be lonely and incivilized and beautiful.
2. Penguin Coast - I felt sea winds and heard bird cries, he though it to be beautiful, but mentioned that there could be monsters in those depths.
3. Marshes - he thought them to be empty, even animals are rare here. My thought was about great and hot marsh with mists and strange aromas in the air.
4. Dragon Valley - that's Mathew who started talking about dragons here imagining that he is a member of some ancient order of dragonriders. I thought about the river turned into the roaring and dirty current during rain season.
5. The City - we both agreed that it's the center of trade and religion, maybe it was a capital when empire still ruled this lands.
6. Cold Mountains - again we agreed on this place. Both had the images of caravans going to some far places to bring luxuries this harsh land doesn't have.
7. Lightning Coast - we both though this place to be usually calm, but with fierce unpredictable storms.
8. Twisted Forest - Mathew felt danger in this place and false sense of safety. For me it was moist and intoxicating with lots of insects and maybe ridden with desease.

So these were the moods

Next time I'll tell you about weather effects and cataclysms of our world and show the basic map of it's biggest, not yet named, continent. Maybe we'll have basic ethinicities worked out by that time.