Missing one item. Post what you have now. Use high quality MP3 rather than WAV. We don’t have to analyze your waveforms as much as hear how you sound. MP3 will let you include more work.
Jumping in without that is just running in a vacuum. Hold you breath for about two seconds so we can get an idea of the background noise and then the first few seconds of a performance.
Most soundcards have a “20dB Boost” setting that can be very valuable for weak microphones, so we may be able to solve one problem right away. Not a clue where to find it, but it’s pretty common and even my older Windows machines have it.
The main difference between the first two and the third is the intimate proximity to the microphone and the absence of room echo. The first two are obviously speaking in a room with hard walls. I had to listen carefully to the third one to tell what he was doing.
Nothing says newbie faster than recording with echoes.
Number two is wearing a lavalier microphone. You can see it clipped to the top of his shirt. You can also see a brick room with a nice shiny hard table. Really difficult to record in that room without echoes. Let’s go with impossible.
I can’t tell what number one is doing, but he’s suffering from Hard Room as well. The joke is I can almost tell how big your room is by measuring the echo. Almost true.
The room isn’t the performer. You are and I can tell you there are no good tools to get rid of echoes. You have to record a clean track right at the start.
It’s true that most built-in soundcards work OK with Skype and not much beyond that. They’re noisy and distorted and there usually isn’t much you can do about it.
It’s been my experience you can do very well with an inexpensive microphone if you cure all the other problems.
The usual recommendation is go with a nice quality USB microphone, but that can have it’s own shortcomings. One of our posters is recording audiobook quality work with a Blue Snowball, but he’s doing it in the quiet studio he made from a broom closet.
Waiting for your sound clip. You might also include info on your computer, operating system, etc. I’m typing on a 15" MacBook Pro with OS-X 10.9.5.