I need a mesh for a dress I made. Help?

I'm completely new to making custom content. I made a dress in Marvelous Designer. I am using this tutorial. I now need to create a mesh for my dress. The problem is that there's no nude mesh for full body (female). I've seen this post, but I don't know how to use blender. It says to append the two blend files for the nude top and bottom, but I can't figure out how to append them (I've looked online for help but can't find any). Is there any other way to create a nude full body mesh? Can you just use a nude top mesh? Thanks!