To get you started faster, follow these simple steps :
-in wed, create a new project and open it
-file, upload from the gateway... follow the steps
-launch wedbing and download the associated satellite imagery (zl18 is good to start with)
-open again your project in wed, you will have the satellite packground included
-you are ready to work
About the contour button, i have read they restaured it in pb14 or pb15.. haven't looked for it though, as I do not like to flatten all airports.
There is another option you can activate via WED, if you want to flatten a specific airport. It it sometimes useful if the mesh is bad. You can find the option if you click on the airport name in the airport hiérarchie in WED.
PS : note that WED does not allow to modify the mesh. If you want to touch that, one option is to use a combination of JOSM, Ortho4XP, and you will have to work on a whole tile on 1 by 1 degree of latitude/longitude. Again, there are a lot of tutorials on youtube.