I don't have 5D or a Viking, but have you looked for an "Import" button? Often under "File" or "Edit" there is an "Import" option. When you click on Import, it will allow you to search for the design you want.
Someone with the programs should be along to help you soon. Martine (mops) and some of the other Cuties are wizards with these things.
I have attached a link that has videos on how to use your software. You may find all you need there.

I didn't upgrade to 5D but do have 4D and one of the best sources of step by step help for me came from a set of insruction books by Tim Frost, also known as Mr. Patience. My dealer sold them but you can find him online at www.mrpatience.com
He sells the books but also occassionally has some free on line pointers.

Open 5D on your computer. Click on the camera icon across the top or "view" in the dropdown window. A small vew window opens. Use the (...) to locate your design from where you have it stored on the computer or memory stick. Once the design is on the screen in the hoop use the tabs at the top right to make addtions to your design such as letter, frames and etc. You have to be in the design tab to save. I have 5D Extra but I believe they are very similar. Also, when you loaded the 5D on you computer it should have loaded a manual someplace. I have found that very useful! I print out sections as I need them. There are more than 200 pages in the manual. It is called "Reference Guide"

Sorry I cant help but if this problem was mine and I had been given the reply you had I would be ringing them up daily asking for a reply. Hope someone here can help

Or you can open the file icon to the left of the blue camera icon and get a pull-down menu. See picture.
The manual shows both methods it in the sample exercises.

You did not mention if you had 5D only or 5DPro It makes a difference on what you are able to do to change the designs Lettering-- change the tab on botton left to letters type in box then click Apply. Change lettering by putting a dot in type of font you want. Each module has a help section. Open a design-File on left side top one left click shows a drop down box look for designs.
Also think about joining Viking yahoo for software--Hope this helps some