Help Tips are usually assigned to an object so that when the mouse cursor is placed over that object, a message related to the usage of that object is displayed.
In 4D 2004, you can create help tips by going into the design environment, clicking on the Tool Box button in the tool bar and then clicking on the Help Tips button. If you have chosen not to display the tool bar, then (from the design environment) select Tool Box --> Help Tips from the Design menu in the menu bar. Click the green "+" button at the bottom to create a new Help Tip. Give it a name of 15 characters or less and then enter the help information in the area on the right side of the dialog.
To assign the Help Tip to an object, simply bring up the properties list and scroll down to the Help section. You can now select the Help Tip you've created.