You need to know the difference between pieces of scenery, some can be walked over while others cant, for example - you can travel over sand but not a tree, this screenshot may help you understand this. The scenery circled in red cannot be crossed, wheras the scenery circled in green can!

Also keep in mind that your character is not jesus, he/she cannot walk on water so be careful where you place it.
While nosing around the games features, you may notice some interesting widgets such as, recourse importers, and databases. The Database is being covered in a different tutorial. However if you wish to use the importer - you should know that it comes with very strict file format rules. It also complains a lot about invalid colour depth, so be careful.
Thats all for this one folks!