I have a tear of bitter nostalgia in my eye to hear that you are so lost.
Is there no one who can take five minutes to show you the tricks?
I hear that Archicad users are easily seduced by free beers.
Not that i would know.
SO:
you can start with the walls, you can start with a slab.
you can start the roof, but that is not fab.
See "Magic Wand" to see how edges can be sought and voids filled automatically. [Wall seeking and tracing edge of slabs, for instance]
Here is why it is difficult to explain rather than demonstrate, since even the most basic of inputs prsents a series of infuriating pitfalls to the beginner:
To make a specific slab:
Set input coordinate method to "relative" not "Absolute"
1: Activate slab tool.
2: Choose rectangular slab option.
3: click [or numerically enter coordinates for] the slab start point,
4: input "x" [keyboard]
5: put in your x distance
6: input "y" [keyboard]
7: put in your y distance.
8: return
x
10
y
10
RETURN
You should now have a rectangular slab of some size.
If you use the polygon slab option, you can draw a series of edge segments with the series:
x
enter value
y
enter value
RETURN
x
enter value
y
enter value
RETURN
until you run out of nodes.
A second RETURN closes the polygon.
Keep playing.
Dwight Atkinson