It's got quite a good user guide and it is worth looking at it because as I say, once you've got the workflow sorted out it's half the battle. You try to move a wall by a millimeter and everything changes out of shape ARRGH! It's a room when you put in the floor and usually for a plan the walls are all you need.) so there is a bit of a learking curve especially when things are snapping to grid lines etc, and they can be very very frustrating. You can build 4 walls and put the furniture in but it still isn't a room. (Creating a room is a different thing and that isn't intuitive at all. They are always a bit intimidating because really you need to understand the workflow to use them and you have to know how to create the walls and the measurements for the walls first before you can get stuck in. The one I have used on the Mac myself is called Sweet Home 3D. Home Design 3D - The best design app on iOS, Android, PC and Mac ! It's not so good if you want to stack up plans but for what you want it might be ideal. You can change the sizes of the furniture too just by tapping on them (from memory but I haven't used it for a while) As you don't want much furniture you might not have to pay but it is useful to use the standard furniture because you get an idea of standard sizes and that can really help with the ergonomics of a room. I'ver just checked and it looks like the basic program is still free and you pay for the furniture packs so you can give that a go if it sounds appropriate. If you want to create odd shapes it's more tricky though and it's better for squares and rectangles.

It's pretty intuitive which you can't really say about the average cad software and you can pretty much have a go straight off the bat. Double click a wall to change the measurements that sort of thing. If you have an ipad or an iphone then with Home design you just drag the room into shape with your fingers and drop items onto it. They have a version for Mac OS but I haven't used it so I don't know how simple it is.

The simplest one I've used is actually for the ipad or phone if you have one and it's called HomeDesign 3D.

Free floor plan for mac