No offense, but this has come up atleast 3 or 4 times in the last week.
Do a search on this site for sump or wet/dry. And look in the diy section for ideas on how to build them.
If you don't understand after that or have specific questions PLEASE ask and someone will be there to answer you. If you like you can send me a message directly and I will return it as soon as posible.
Later,
Dr Joe