When you cannot supervise her, either confine her to her bed in that room, or put her back in her den. Once she accepts this room as an extension of the den, the go on the the next room. If you follow the instructions so far, your dog will be housetrained in due time. One way to speed up the process is to praise and reward your dog each and every time she eliminates in her toilet area. It is equally as important not to reprimand you dog for accidents and mistakes.
Reprimand usually confuses the dog and slows down the training process.
If your dog continues to soil her den, either you have left her there too long or the den may be too large an area for her. Take her to her toilet area more frequently or establish her den in an even smaller area. Urinary tract problems and medical conditions can cause your dog to soil her bed while she is sleeping. Some dogs drink excessive amounts of water out of boredom or habit and therefore have to urinate too frequently. If this is your dog, limit her water, take her to ther toilet area more frequently and give her activities to do so she isn't bored.