Antonio, it's not a question of being boring. There's no problem to help you but Facebook is simply not the place for support requests. You should also be a little more patient. Don't expect an answer about anything immediately after you post a question.

If you installed the program with [font=courier new]/j3d.version=1.5.2 /os.arch=x86[/font] parameters (did you?), the program will run in 32 bit and the max memory you can request will be 700 MB. So trying a higher value might simply make Sweet Home 3D fail as you tried.
Note also that [font=courier new]-Xmx[/font] option must be followed by a number and a letter (m or g for MB or GB).