First select one or more catalogs that you would like to search. Then choose whether you want to search by target name or by position on the sky. Then type in the requested information (name or RA/Dec). Finally, click on the Search button.
If the search is successful you will see a list of one or more catalog entries to choose from. Click on the entry that you would like and then click on the "Select Object as Target" button. This will take you to the "Image Chooser window" so you can select an image of this target.
Note that the VTT does not support creation of a new proposal target using the "Select Object as Target" button. So this action will not affect the content of the proposal. APT has it's own Target Selector window (which you can get to from APT's target folder when the Form Editor is the choosen tool) which can be used to create a new target in your proposal.
If you choose to retrieve an image from the DSS or 2MASS, you can do so by RA/Dec or Object Name. You can also decide how large a piece of the sky to retrieve (obviously the larger the image, the longer it will take to transfer). For 2MASS images you can also select the band to retrieve (J, H, or K). After you specify these parameters, click on "Load Selected".
If you choose to retrieve an image from NED, you will see a list of available images of your selected target (with thumbnail images). Click on the entry that you would like and then click on "Load Selected". Note that if there are no NED images of your target (or NED can not resolve your target name) the list will be empty but you will not get an error message.
If you choose to retrieve any other type of image, please read the instructions on loading other images.