The label widget provides a read-only text label, and it has attributes that let you control the position of the label within the display space. Most commonly, however, you just need to specify the text for the label:
label .version -text "MyApp v1.0"
The text can be specified indirectly by using a Tcl variable to hold the text. In this case the label is updated whenever the value of the Tcl variable changes. The variable is used from the global scope, even if there happens to be a local variable by the same name when you create the widget inside a procedure:
set version "MyApp v1.0" label .version -textvariable version