Hi Ruediger, Welcome to Talkgraphics

First are you still wanting to know how to do this in Xara Photo&Graphics Designer? As you have posted this in the General graphics chat you could get answers for using any software. If you want I'll move the thread (or one of the other mods may move it) to the Xara Graphics Chat forum.

Second we need to know the exact version you are using. There may be different methods depending on what tools are available to you.