It is not entirely clear what you want. First you say you want to write in
the text instead of picking from a drop down list, then you say that you
want to select from a drop down list.
In any case, the answer is similar.
Bar Text comes from fields (also commonly called columns). In your schedule
each task has a name field, start field, resources field etc. These are
displayed on the left (table) side of your schedule. By going to view
menu/bar styles you can change which field you want to display and where it
is displayed. For this example pick the top blue bar and set it to display
Text1 to the right of the bar.
Now, since you are considering displaying the information in one of the text
fields, you will need to make that field visible so that you can edit it.
The easiest way is by simply going to the insert menu, selecting column and
then choose the text1 field. At that point you can write whatever you want
in the text1 field and it will show up on the bar at the position you have
chosen.
If you want to have a picklist for the values in text1 that is a separate
issue. To do that simply right-click on the header of the text1 column that
you just inserted and select customize fields. In the dialog box that comes
up there is a section to set a value list for the field. Choose whatever
options you want there and you will then have a value list for that field.
There are other things you can do with the fields like using custom fields,
renaming them etc. which are also useful.
-Jack