make a website summary

[rakibtg]

i need to make a php function which will summarize a website content.  the idea is to get all those content using Simple html dom parsar

, then match some lines with the keyword and return them. i know how to fetch content, but can't understand how to match the keywords      with lines, then pick the most matched lines! later, i found this great article http://stackoverflow.com/questions/1195947/best-practices-on-displaying-search-results-with-associated-text-snippets-from-a#1201464

 but cant configure!

 i wish something like this > http://smmry.com/ as a beginning prog. i can't understand how to do this ... pls pls help me