Hello,

We created an user documentation, press F1 to use it.
As new user, you should read this. Many things are explained like how to use Real work allocation screen.

Here is how to enter real work :

On Project : you cannot. Project only sums real work entered on activity
On Activity : through real work allocation screen (resources must be assigned to the activity to enter real work)
On Milestone : you cannot. Miltones don't have work nor duration. (have a look at the definition of a milestone)
OIn Action : you cannot. ProjeQtOr don't follow work on Actions. Think of Actions like "TO DO" list