Interact with the site that opened Tools

Question

 I would like to know how to interact with a table added in the location that was opened by a tool "webBrowser" so that I can add value to a cell on the basis of containment row this cell boiling a certain value.
    And also how to add the statement "for" to mobilize all the cells that the condition is met
    in c#
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    I hope that my question is understandable.