You will be presented a screen similar to the one below:

Again, you see a public and a private textbox. To the right you will see some specific weather information controls (depending on your settings, you can see more or less weather rows and hide the windrose).

Suppose it was chilly and raining. Set the temperature to 10 degrees and click on the weather image. A dropdown is displayed. Select rain and notice the icon is changed.

Next set the wind. It was 6 Beaufort from the South, so click the south arrow (it should become red) and enter "6" the middle textbox. When you are done, press "Save". This will take you back to the adventure editor.

Time to add some photos and videos!