It is so simple:
...
import org.apache.wicket.extensions.markup.html.form.DateTextField;
import org.apache.wicket.extensions.yui.calendar.DatePicker;
...
DateTextField df = new DateTextField('wicketID', dateModel, "yy.DD.mm");
df.add(new DatePicker());
form.add(df);
Basically, you create a normal DateTextField and add a YUI Picker to it. that's all.
to use
Edit: answer questions in the comments:
user500129: maven ? . , yoi -. maven:
<dependency>
<groupId>org.apache.wicket</groupId>
<artifactId>wicket-extensions</artifactId>
<version>${wicket.version}</version>
<type>jar</type>
<scope>compile</scope>
</dependency>
maven, maven, wicket.14.14 : http://mvnrepository.com/artifact/org.apache.wicket/wicket-datetime/1.4.14
,