If you are having trouble using large rubber stamps, here is a tip- use your bone folder! I made this method up a long time ago when I first started trying to use the large background rubber stamps and I teach it in my Introduction to Rubber Stamps class. Especially if the stamp is not deeply etched, the larger images can be very difficult to stamp and quite trying for a beginner stamper.
Generally, you place the paper on your desk or table, and then ink your stamp and press it onto the paper. You can do it this way if you like, just make sure that you walk your fingers all around the stamp, to make sure there is good contact with the paper all the way around.
However, I find it much easier to ink the stamp face up, and place that on the table, so that the rubber is facing up towards you. Then I place the paper on top of the stamp, hold it steady with my left hand approximately in the middle of the stamp. I take my bone folder in my right hand, turn it on edge, and drag it from the middle of the stamp, along the paper and out to the right. I then hold the paper still with the bone folder, and move my hand to the right of the mid point. Then I drag the bone folder from the middle out to the left.
I try to drag the bone folder a couple of times in each direction to make sure I get good contact all over. Then I carefully lift the paper off the rubber stamp. A perfect stamped image every time (well almost every time 
)!
It may take a couple of times to get the hang of this, but for most people it really works!
Stay tuned for an alternative method that I have just thought of, that will help stamp the larger and more difficult stamps. 
I will post that technique , including pictures, soon!
