I am using GSS 2.01 and have not used 7.5 in a couple years so my instructions may not be precise to what you will see with 7.5
Assuming you have already installed the ghost console client to a target machine.....
You need to create a new task.
To pull the image:
click on tasks in the left pane of the console. In the right pane you can right click and choose "New Image Create Task" This should start up an empty template for an image creation task.
Set a name for the task.
Pick a source machine (one of your client computers that has the console client installed), select source drive. Only select the source partition if you are only interested in making and image of that partition.
Assign an image name. There may also be options for compression of the image, that is your choice entirely. Setting the image name will actually create a new configuration resource image that the console can use for redeploying to a machine alter. So when you click on browse for the image name click on "Images" in new window, then click the "New" button, then "New Item". You can then name the image and select a location to save it to.
At the top of task window you should see more tabs. The "Network" tab allows you to set unicast or multicast parameters and a speed if you have a problem with network saturation. There may also be a sysprep tab but I am not going to go in to that as I don't use it and you wanted a basic tutorial.
I am going to leave the deployment up to you, the operation is similar but you won't be creating an "Image Creation Task" to redeploy.