Don't know why but in my case with PhotoBucket I "SHARE" as thurin illustrates BUT when I click on the IMG - I ALSO NEED to go to my browser drop down EDIT window and COPY before I can then paste on BF. An EXTRA STEP, otherwise Photo Bucket works fine for me. I haven't always needed to do the COPY part - used to be (and sometimes still can) simply click on IMG then paste in BF.
If you need - knowing about this extra step could save you some aggravation.
Also - regarding the size - I never send my photos to PB without first using a photo program on my computer to scale the photos to approx. 5" wide (no wider than 6" - I think they get nearly unviewable on my lap top screen in BF so I can only imagine how they scale to a hand held device) and no more than 220 pixels (110 seems to view fine on most devices).
Ray