reload existing window from another window

hi!

I have logg in page, after clicking loggin the pop up window apiears and
if user loggins it closes,
  I want to reload from were page were user have clicked to logg in, how do
I do it?

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Thanx in advance
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BTW. I know my english is not best in the word, so please stop bugging me  
about my spelling. And yes Iam sorry you don't understand what I mean, but  
there is no point to yell at me. Have a nice day.