Auto Fill in a Spreadsheet with Data by VBA

Please use VBA to write the code. I have a few categories of key words(say 5 categories (category A-E) with around 10 key words in each category) in a spreadsheet, if i manually paste text into a column (say B1 in column B), I want the code to find if one of the key words in category A is in B1. If so, then set the key word as the value of C1; if none or more than 1 key words from category A are found in B1, then set C1 as blank and filled with red. Do the same thing to category B, and set the key word found to D1. and so on and so forth, until all the categories are scanned to finish the row. The categories will be defined by lists in a separated sheet in the same book. The code should allow me change the key words (add, remove, edit) in each category and the categories (add, remove, edit) as well.