New. Please help, thanks.

I really need help from those more experienced to install.
I am new to Mac OS and of course am used to just clicking, downloading and opening. This is much more complex but I'm trying to figure it out. I'm running Lion. Can anyone give me something easy and step-by-step? I've downloaded kdenlive and extracted/ expanded the files. I've also downloaded Mac Ports. What else will I need and how can I get it running? I am not too computer-savy but I know or can figure out pretty quickly my way around programs once they're opened. I just really want/ need an editing program and iMovie just isn't cutting it for me.
For my PC I typically use Sony Vegas Pro 8, 9 or 10 and sometimes Adobe Premiere.