Nowadays, more Virtual Environments (VEs) are becoming available on the Web. This means that VEs are becoming accessible to a larger and more diverse audience. It also means that it is more likely that the use of these VEs (i.e. how to interact with the virtual environment and the meanings of the associated virtual objects) may be different for different groups of persons. In order for a VE to be a success on the Web, end-users should easily get familiar with the VE and understand the meanings of its virtual objects. Otherwise, the end-user may be tempted to quit the VE. Therefore, annotations and the creation of navigation paths for virtual tour guides become important to ease the use of VEs. Most of the time, this is done by VR-experts and the annotations are very poor and often only text based. This paper describes an approach and associated tool that allows a layman to add or update annotations to existing VEs. In addition, annotations are not limited to text but may also be multimedia elements, i.e. images, videos, sounds. Furthermore, the approach (and the tool) also allows easy creation of navigation paths and tour guides, which can be used to adapt a VE to the needs of a user. The paper illustrates the results by means of a real case, which is a reconstruction of a coalmine site for a museum.