You'd need to create the image on a higher pixel count canvas. When you sit down to create an image, go to File > New Painting and then click on the "Print Size" tab at the top of the "New Painting" Panel. Input the dimensions you expect to print at (or even double it, if your computer can handle the load; the larger, the better, since you can always downscale them, but you can't always upscale). Since you printing, you should probably use a 300 DPI setting (though some members here say they've had decent results with only 150, but again, higher is better). How large you can work, will depend on the power of you computer system, however.
Also, When i create a stencil, how come it wont let me use the 'bucket filler' properly? it just fills up the whole page rather than inside of my custom made stencil, yet it works properly for the ArtRage 4 stencils provided.
*i have double checked all my lines and they all connect*
Before do anything else, check out the stencil to see if it's red, white, or blue. If it's blue, it's set up to be a "Guide" stencil, which means the tools will bleed beneath it. Right click the stencil and set it to use a "Ruler" (white) or "Stencil" (red) mode. They'll both keep the paint retained (assuming the stencil is set up properly; read below).
The stencil system works off of images (so any image may be imported into ArtRage as stencil). The images are interpreted by the stencil system as being black and white (even if they have color in them). The darker the area is on the image, the more paint will be allowed through that area when used as a stencil. The lighter an area is, the less paint will be allowed through. So a pure black spot on an image, will allow the most paint through it, while a pure white spot on an image, will complete block an paint from getting through. So this means any areas of the image that would be grey, will allow only a certain degree of paint through as a stencil (the darker the grey, the more paint allowed through). It's a lot like screen printing.
So, assuming you had the stencil set up as a "Stencil" mode stencil (colored red)... my guess is that your stencil doesn't have a completely white border, which is allow the paint to spill out into the "grey" areas and out over the rest of the canvas. If you don't believe that's the case, then perhaps you could post the image (the one you're using for the stencil), so we can see what it looks.
Nothing is easy to the unwilling.