This new woman at work really isn't cutting it. I'm going to tell her she is not good at her job
I don't know if you should. Why do you think she isn't good at her job?
She's just useless
At the most basic level, what you're doing isn't bad. It's beneficial to call out a colleague's poor performance at work. Just make sure to be professional about it or you might end up hearing from HR!
It's fine. I'll act like I'm trying to help her and everyone will love me.
Actually helping her out would be a great thing to do. She will probably really appreciate some pointers.