Creating a Table

I have created a table using the html editor in WordPress but when I publish the table it erases all of the code except for the first table row. Is there a plug-in or something that will allow me to create a table. WP-Table is too simplistic (unless there is a way to modify it).

This table will be used to track student progress similar to a bar graph and I need to be able to update it fairly easily and define the background color in each cell based on the student’s level.

I am not an expert with html or using blog software – in the learning stages – so responses should assume that I don’t know how to do anything.

Any suggestions? Thanks in advance.