Getting text from TextBox

First you need to have the class being used as the ViewModel set as the DataContext for the View.

Second you need a property in the ViewModel that will be bound to. If there is going to be changes in the ViewModel that have to appear in the View, then need to inherit INotifyPropertyChanged in the ViewModel class. Whenever you change the value of the property you need to raise the PropertyChanged event with its event args containing the name of the property:

public string PropertyName
{
    get { return propertyName; }
    set
    {
        propertyName= value;
        if (PropertyChanged != null)
           PropertyChanged(this, new PropertyChangedEventArgs("PersonName");
    }
}

Third you need to do the binding in the View:

<textbox text="{Binding PropertyName}">