how to user HTML tag and php in wordpress
Here is tool you can use to convert your html code to publishable online.
http://web.forret.com/tools/html.asp
There is a plugin available called WP-Table that allows the creation/insertion of tables (aside from the standard one in the post)
However it’s no longer being supported by the author (Alex Rabe – he’s very busy with NextGEN gallery) and to make it work with 2.5+, you’ll need to make an edit.
The forum thread with the fix can be found here: http://wordpress.org/support/topic/168271
Although (apologies for the self-promotion here – this is my disclaimer) you can read it in a post-like format here: http://www.wpsnippets.com/2008/06/wp-table-plugin-fatal-error-fix/