I want to make a rectangular hole in the plane?like a window opernign in the wall how to do it?
Tab into edit mode, select the 4 vertices (A until they are all selected), extrude (E), ESC (to not move new vertices along the normal), CTRL+W -> Smooth (a few times). From there resize /adjust as you like.
can i first make a plane cut holes into it then extrude it ?
You can do it any way you want. This is what I am referring to (do the same thing to a plane).
Then after the smooth, delete the center face (not verts or edges, but face).
This tutorial also does the same thing (specifically for a window). http://library.creativecow.net/ciccone_paolo/blender-survival-guide-11/1
I don’t think it is good ways to do this
Well then you could use loop cuts. Tab into edit mode and press W. Select Subdivide Multi, enter 2 for Number of cuts and click OK. Delete the center face.
There’s always more then 1… 2 … 3… ways to model the same thing, and there’s no right or wrong so long as it accomplishes what you are attempting.
Personally, when adding detail like a window into a plane, i use the P key when it is selected in edit mode to make it another part, change to that object, go into edit mode and subdivide multi 2. Then i do the hole/frame/45 minutes of bugger all and then i merge the vertices on the edges to the corners so it’s still only got 4 verts defining the exterior, that way, when you rejoin in, it’ll fit right in.
Alt+ M to join (strangely, i always join at last. Your choice though)
CTRL+J to join different objects.