Replacing towel rod in tile shower?

[dottyblue]

Does anyone know of any blogs that cover this as a DIY?? Preferably with pics. Or a good how-to website. Googling is giving me a lot of non-answers

We need to replace a cracked towel bar in our rental before we move out in a couple of weeks (why on earth anyone thought a hollow, plastic bar was a good idea is beyond me...)

TIA!