Here's an easy way to weld all the letters of a word together in the Design Studio:
1) With the DS open and your cursor set on the mat where you want it, type the first word (all the letters) with no spaces between them. Then, in the kern box, type "-0.25" (without the quotes) and hit the apply button. This will overlap the letters. If they overlap too much, experiment to see what overlap you like by changing the kern number.
2) Then, highlight each letter and click weld.
Here's a tip: To highlight a letter or object in DS, click on a line segment of the letter or object. This will bring up the bounding box (the one with arrows). I spent many frustrated hours trying to get the letters to highlight.
Also, another tip: If you can't get the cursor to move on the mat, adjust your double click speed. It doesn't seem to handle super fast double clicking well. Slow it up a little bit and see if that helps.
One more thing, the DS program only allows ONE computer to cut your creations. So, if you have DS, you can load it on multiple computers, in order to create things, BUT you may only cut with one of them. I assume it is the FIRST one you load DS onto. I am really cranky about this because a day after I loaded DS onto my Windows laptop, it decided it wouldn't take a charge from the power cord anymore. Arrrgghh!