How do you add a logo to a trademarked wordmark?

I don't understand the question.

A trademark is a logo that has been registered as such. There are entities that solve this for you, google for register trademark and you'll find solutions.

A wordmark is actually a logo that's made out of text. Such as the new microsoft logo. Or, if you look at, the logo you see is also a wordmark.

So, what you do actually want to achieve? Do you want to add some graphic to the existing logo you have? Or trademark it?