Have you tried Googling "topiary trimming guide" or another similar search phrase? You might run across what you are looking for that way.

based on the drawing, the wall where the bed is. HOWEVER, you mentioned that this drawing is not a true depiction of the furniture you will use and the wallpaper. if that is the case, i think the wall paper can work on either wall, it all depends on how busy this wallpaper is and how "plain" the bed is. if you go with a busy wallpaper behind the bed, you may want to keep your bed and bedding on the minimal side so that there is a good visual balance to the overall composition. if you go with snazzier bedroom furniture, then a busy wallpaper may be a bit much and you may want to put it on the other wall or use a textural option to serve as the bed's background rather then another focal point.

My last household purchase was new sliding doors to the outside from my dining room. This then led to the building of a deck, new railing on said deck and existing terrace, new blinds as the old window length curtains no longer did the trick, then the paving stone path to the deck from the garden gate, some new planting to accommodate that, AND outdoor lighting for what has now become an alternative entrance to the house! Oh, and painting as well. So I can liken my last purchase to a bit of a triffid - it kept growing! But SO worth it! It has added another room/space to my house, increased light and warmth, added value and created a more welcoming entrance than before. Love it!

I have no idea where you could get that from. Maybe try Amazon.