The Challenge - Install your software.
Like I said above, this tutorial series is going to be based around my personal favorite (free) software. The tools I like to use for permaculture design are:
Inkscape - This is a vector drawing program, which means that you can make images that have teeny tiny details and zoom way in without losing image quality. The alternative is called "raster drawing," and is based on editing pixels (think photoshop). The downside of that is that if you zoom in too much, everything gets grainy and you can't add any more details. With a vector program, you can draw a 100 acre property and still zoom in enough to draw individual plants, if you want. You'll use this to draw the actual design.
gimp - This is a raster image editing program, useful for retouching photos or stitching together background images that you get from screenshots (you'll see what I'm talking about in a future challenge). You'll use this to clean up imagery you use in your report, and to create a backdrop for your design.
libreoffice - This is an office productivity suite, along the lines of Microsoft Office. The advantage it has over Microsoft's stuff is that it's free while being mostly compatible with Microsoft's formats. If you already have MS Word, MS Excel, etc, then you can skip this step as it would just be duplicating functionality. You'll use this to write your design report.
I used to recommend MWSnap, but after a lot of awesome feedback I have better recommendations now for a screenshot tool! Any of these tools will do what you need - install one that's compatible with your system and you're ready to go. Credit goes to Ty Morrison, Quintin Holmberg, Erik Little, and Manolis Karamous, all of the permies forum, for these recommendations:
SnagIt - Windows,Mac,Chrome
GreenShot - Windows
ScreenCloud - Windows, Mac, Linux, also automatically uploads to a cloud service or web server, which is handy.
Another new addition (updated 5/14/2014) is Google Earth. This has proved very useful in later tutorials, so I recommend installing it as well.