How do you make blurr on camera dslr?

dont really know what you mean... but one method is to take two exposures, one with the subject in sharp focus, another with out of focus image (same subject) and combine the two images with a mask in photoshop. another effect is to use a double exposure, and throw one out of focus. both techniques require still-life subjects and a tripod otherwise, blur is generally to be avoided in photography, but can be caused by camera or subject movement, bad focus, zooming during exposure, or having dirty filters on lenses, shooting through screen doors... etc.