How can I get a track of a guitar strumming an A7 chord? Or any other added note chords? I don't have instruments of my own so I'd like to use only GarageBand for Mac instruments. I can play the chord using musical typing but that isn't guitar strumming.

The basic idea is to find aloop with a rhythm you like, and then add the 7th note - for a real instrument loop in a separate track, for a software instrument loop by copy and paste from notes in the piano roll view in the track editor. Then transpose the loop to A by shifting the pitch slider in the track editor.

Regards

Léonie

Jane, what key is your project in?

For example, assuming your project is in Dmaj, and you want to add a loop in A7:

• The loop "Acoustic Noodling 01" is a real intrument loop; meaning GarageBand will add an audio file to the project, not a midi file. So you cannot change individual note in the track editor. All you can do will be to transpose the loop to A. When GarageBand adds a loop, it will transposed to the key of your project, in our example Dmaj. To turn it into an Amaj loop, you will have to transpose it using the lider in the Trackhead - either 5 halfsteps down or 7 halfsteps up.
• After adjusting the slider yyou will notice, that the loop now is marked by a -5.

To add a seventh, you will need to create a seond track with a similar sounding instrument and play the missing "g" in the rhythm of your strumming.

Use a software instrument, then you will see the notes you are playing in the piano roll as bars. You can shift them to correct the timing and drag the ends of the notes to adjust the duration.

If you do not have a midi keyboard, you can use the built-in musical typing window (⇧⌘K) and play it by pressing corresponding keys on your keyboard.

For a future recording I would just like to have a guitar backing track strumming through chord progressions, including dominant sevenths (for example a simple I-IV-V7-I).

For a Chord progression - use the pitch slider to transpose the regions - here i set it to I-V-IV-I.

The hard part is the "7". If you use a real-instrument loop without seventh, you need to add the 7 in a different track.

If it is a software instrument loop you can shift and copy and paste single notes, like I have show in the first screen shot.

I honestly just thought this would be a lot more straightforward.

If you listen to the provided loops, they are mostly already playing chord progressions. So you just have to find them.

Ans the JamPacks, if you have them, have many guitars that are playing chords, when you are pressing a single note, for example the Flamenco Guitar in the world music JamPack,