I'm a poor guitar player and never get through a piece without making several mistakes, so I won't apologize for the obvious ones here.
When it is your composition, then there are no mistakes, just spontaneous improvisations. Nice playing and good sounding guitar. What make is your guitar?
Do you have any music player that will play mp3s? Windows Media Player is often the default player for mp3s. If it isn't you can change that where you set the default programs for certain file types. I'm not an expert on any of that, though. I wouldn't worry about it because I'm just not that good on guitar.
A laptop should still be able to play music I think, even if the sound quality isn't great. Someone else should know. I've never had a laptop.
Marie, it took me a while to figure out how to play attached mp3 files here. I had to first download the file to my computer. [Just clicked on the file and it downloaded automatically.] Then used a media player on that file. Yours may be different.