If you are a more visual person and have troubles learning from ASM in 28 Days or similar tutorials, this might help as well, although it is still not fully finished and each file are separate:
http://ourl.ca/4673
If I remember, it is not meant as a full tutorial, though, but rather a complement to ASM in 28 days (it takes a more visual approach). There was also an abridged ASM in 28 days file somewhere on that site, but I forgot where it is located.
Alternatively there in ASM Guru, which I seemed to understand slightly better than ASM in 28 days in my 3rd attempt at learning assembly, but it is for the old TI-83, not the TI-83 Plus, and I have heard that in the more technical parts of the tutorial there were some errors. I have heard that some people learned ASM successfully with it, though. If I recall correctly, tr1p1ea, the author of Desolate, used it, but it has been a long while since we discussed about his early days into Z80.