The Citrix client for Mac OS X is installed locally on your Mac. If you would like a more integrated method of connecting to a smaller number of Virtual Desktop applications on a regular basis, you should use the Citrix client for Mac OS X. If you are using it for the first time, you should first read this article about how the client works.
An ICA file is created to define a Virtual Desktop application to which you would like to connect. You can define individual settings for each ICA file according to what is appropriate for that application.
1. First you will need to install the Citrix Client for Mac OS X. For those instructions, click here.
2. The Citrix ICA Client Editor is an application that is installed along with the Mac OS X client and is used to create ICA files. Browse to the directory as shown and open the icon for the Citrix ICA Client Editor.

3. This is the initial window of the Citrix ICA Client Editor. First, you will need to configure the default settings that will apply to all Virtual Desktop settings. To access these, click the Default Settings buton on the lower left.

4. This is the Default Settings window. For the Mac OS X client to connect to Virtual Desktop applications, you will need to tell it the web address of the Virtual Desktop service. On the Making a Connection tab and Server Locations subtab, change the Network Protocol dropdown menu to "TCP/IP". Then click Add and type "virtualdesktop.uiowa.edu".

5. Next, you will want to configure the desired size of the window in which the Virtual Desktop application will appear. Click on the Connection Properties tab and the Windows and Sounds subtab. The two important settings here are:
Windows Size: It is recommended that you change this setting to "Seamless". Seamless Windows means that you may dynamically resize the Virtual Desktop application instead of being stuck with a static window size.
Windows Colors: This defines the color depth of the Virtual Desktop application. It is recommended that you select the setting for "Millions". Current applications will likely appear washed out or grainy if you choose "Thousands". However, if your internet connection is fairly slow and would like improved responsiveness, you may do so.

6. The next important default setting you will configure is Drive Mapping. Remember, when you are working in a Virtual Desktop session, it is actually running on a Virtual Desktop server. This means that when you try to save a document, it has to save it over the network to a different location than one of the local hard drive on the server, which is not permitted. This is where Drive Mapping comes in. When you define a mapped drive, you will be creating a network drive that points to a location on the hard drive in your Mac.
By default, the client will map a drive that points to your /Users/{User} directory on your Mac. Mapped drives can be viewed by clicking the Drives and Devices tab, then the Drive Mapping subtab. (See mapped drive C: in the image below.) You may also modify whether the mapped drive can have Read access or both Read and Write access by clicking on the icons to the right.

7. To add additional mapped drives to other locations on your local Mac hard drive, click the empty row by drive D: (or whatever letter you would like to assign), browse to the appropriate folder on your Mac hard drive and assign it the appropriate Read and Write permissions. (See the second image below. Drive D: is mapped to the root of the Mac hard drive and drives A: and B: are now disabled.)

8. This article has described the most important settings that should be setup prior to using Virtual Desktop. However, there are several other Default Settings that can be configured. Before clicking the SAVE button in the lower right, you may wish to browse through the different tabs and subtabs to see if there are other preferences you would like to define.
For instructions on installing and using the Citrix client for Mac OS X, see the main Virtual Desktop Documentation page.