A Picture is Worth a Thousand Words, But a Song is Worth a Million.
Audacity is one of the easiest programs I've ever used for simple sound edits. I process the sermons for my church every week. We record the entire service, then I break out individual parts to upload them to our webserver. To highlight a selection, just click on the point you want to start, then go to to where you want to end. Hold down the shift key and click. Everything between the two marks will be highlighted. It works exactly like text in any document. In other words, if you want to select from one point to the end, you just click where you want to start, then [shift]-[end], and everything you want is selected. Use control-c to copy, and control-v to paste into a new recording if you want. Or select the bits you don't want, then hit delete.
Once you have everyhing you want, you can use control-a to select the entire recording, and select 'effect' then 'amplify' to boost the levels of everything.
For simple edits, audacity is easy. It's when you start doing multi-track stuff that things can get more complex.