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Software has been discussed in many threads. It could take you a day or two the read all that has been written.
To start, assuming you have a PC, you should learn the editing software that came with your camera. If it is a Sony or Panasonic, it will edit "losslessly". That means that since there is no "rendering" or "transcoding" the output result is as perfect as the source. However, to achieve "lossless" many creative features and tools are missing. I know nothing about Canon software.
If you have a PC, Windows Movie Maker is free from Microsoft and works pretty well.
If you have a Mac or find the camera provided software limiting, I think the most common and popular 3rd party editing software is Adobe Premier Elements. Now in version 11 it works well with current AVCHD formats. There are versions for both Mac and PC. There is a wide and abundant variety of learning resources.
Perhaps next on the list is Sony's home version of Vegas. It runs on PCs, not Macs, and has lots of fans here.
These two are under $100. Both Adobe and Sony have pro versions for around $600. There are about 20 other 3rd party editors on the market.
Mac owners like iMovie and Final Cut Pro.
When and if asked, I usually try to make the case that the editor you pick has less to do with results than taking the time to learn and master whatever you buy. Personally, I found the wealth of learning resources important and have focused on Premier Elements 11 as my primary editing software.
Few amateurs ever thoroughly learn more than one editor. They are too complex. You won't find many that can actually compare them. Even pros will master one and stick with it. Only if employment forces change, will they learn a new one.