mmm....... I'll see if I can help you a little bit.
First tell me what program you are using to try to reduce them?
Have you looked at Irfan View?
www.irfanview.com
The size limits on the forum are probably 5 times more than you SHOULD need to get a big picture up. (size as in pixels and/or kb's)
If you do put up a big picture you will only see it in a reduced size (thumbnail) until you click on the picture.
Most software for tinkering with a photo can resize them either by pixel or by %.
eg. 30% of original
or
If you know the limit is 400pixels you can set it to that size.
Always make sure "keep aspect ratio" is ticked to keep proportion correct or you may end up tall & skinny or short & fat.
So......... ???