Read through the documentation, but it's really very simple compared to the older Linux distros. Here are some notes from my limited experience:
1) I'd install Linux on a separate drive. This is not absolutely necessary as I've also run Windows and Linux from the same drive, but it makes your life easier the first time around.
2) Read up on partitioning. Even though stock configuration will work, you can always customize it to suit your needs.
3) Check for hardware compatibility. Now, in my case, everything works fine under Linux, with the exception of the el-cheapo webcam and chances are it will work with yours.
4) Installing apps is very simple. You can access some repositories of applications directly via your OS, for others use the APT tool, which makes it very easy to install apps on Debian-based distros like Ubuntu. If you can't do either, website instructions usually make it very easy even for a total beginner.
5) For security reasons, don't give your default account administrative privileges, like you do in Windows. For any administrative stuff like installing apps, you can either temporarily log in as root (make sure you change the root pass) or use the "sudo" (superuser do) command.