Hi Luisa,
Welcome to this Microsoft Project newsgroup
Firstly, you are stronly advised to never enter any dates and times other
than the Start Date of the Project. Project is designed to calculate Start
date from the Finish date of its precedecessor and the Finish date based on
the Duration of the task. Entering dates will cause constraints to be set
up which will adversely affect the flexibility of your project.
However, to answer your question, Format/Layout.../Date format and chose a
date with a time.
FAQs, companion products and other useful Project information can be seen at
this web address: <
http://www.mvps.org/project/>
Hope this helps - please let us know how you get on

)
Mike Glen
MS Project MVP