The map is nearly ready to use. We have to add just some additional information for the freeVikings game engine. First we add information about the solid layer.
Tiled gives you a possibility to have a multi-layer map and freeVikings support them. Usually you have one layer, which is called "solid layer". It's the layer of solid tiles which the vikings can't go through. Then you can have one or more layers, which are there just to make the map nicer. But of course the game engine doesn't know which layer you want to be the solid one.
From menu Map choose the item Properties. A small window will pop up, where you can edit a list of key-value pairs.
Add a new pair with key "solid_layer" and value, which is the name of the layer you want to be solid (names of layers are in the layers panel on the right side of the Tiled window).
Tiled sometimes "forgets" the last property from the list, so it can be useful to add one more property (e.g. key "axb7", value "7785") which would be forgotten if Tiled had a bad day. (I haven't still found out when and why this error in Tiled occurs.
Now you can save the map, it is ready to use.