What type of camcorder did your original footage come from?
Did you ensure that your project used the preset for this format and resolution of video?
You can find more information on using project presets in the first of my free Basic Training with Premiere Elements tutorials at Muvipix.com.
I used HD720p footage from a Canon EOS 7D dslr. And I have no idea if i used the right preset, the project waqs originally created in PE7 and then transferred because the program was so laggy and crashed so often i got the new one.
Video from still cameras nearly always has to be converted to a more standard video format -- such as a DV-AVI -- before it will work in Premiere Elements. More information, including how to convert the video, is found in the FAQs to the right of this forum.
Once it has been converted to DV-AVIs, you can edit the video using the standard DV project preset.
That black bordering is almost always a mismatch between the source footage and the Project Preset. The Project Preset must match the source footage 100%, or there will be issues.
As for DSLR footage, this ARTICLE has many links, that could prove very useful.