[FrankHudson]

Garageband is free and will likely run on your MacBook fine. You have a mic. You can presumably play and sing. There are other free or low cost options, but GB can be presumed as capable of what you want to do without adding any cost.

There are of course a lot of ways to improve things, but you've expressed that you want to get started with what you have. You'll need to learn at least basic GB functions. I think there are a goodly number of free resources to help you learn how GB works.

What kind of recordings are you envisioning? Just solo guitar and voice? If so,. you don't need to learn too much about how GB works. If you want to add more to your recordings, GB offers options in that regard, even with no additional equipment. And you could (if you want) add a second vocal (harmonize with yourself) or additional, overdubbed guitar parts if you own some headphones or even earbuds. You could also decide to record your guitar and voice in separate passes. All these other options are more complex, but offer lots of possibilities, but when getting started you can (and maybe should) start simple. I'll assume solo guitar and voice recorded simultaneously.

If so, your next task is to find a location to record and place your single microphone to best capture a good balance of your guitar, voice and room. For best quality don't rush this step, and when you find it, note it so you can repeat it. To a significant degree quality of your performance and material can trump recording quality, but doing the best you can doesn't hurt.

Where to host your recorded material is another question. People do different things, and from other threads recently here those that offer recommendations seem to have strong opinions about this choice. I'll let them weigh in on this. Not really my area as I use methods that have a (low) cost and may not apply to you if you are seeking to minimize cost.