You need a few basic things to begin programming.

1. Calculator. A TI 83 Plus, TI 83 Plus Silver Edition, TI 84 Plus or TI 84 Plus Silver Edition is needed.
2. TASM. This program "assembles" the assembly code you will write to code that the computer understands. Tasm did not work with enclosed examples. Downloading executable files via the internet is always risky. Does not work for Turbo Assembler 5 code.
3. TI 83 Plus Include File. This text file assists TASM by giving it necessary information when assembling. Does not recognize instructions.
4. DevPac8x. This program changes the code that TASM has assembled into a file that you can transfer to your calculator.
5. TI SDK (Software Development Kit). Also known as the TI 83 Plus Flash Debugger, this program allows programs to be tested on the computer for errors without having to transfer them to the calculator.
6. Linking cable. A linking cable will allow you to transfer your programs to the calculator from the computer.

Now that you have everything, you will need to set everything up. I highly recommended that you follow the examples I give.

1. Make a folder where you will put all your ASM (assembly) files (e.g. C:\ASM).
2. Unzip the TASM folder into a subfolder in your ASM folder titled "TASM" (e.g. C:\ASM\TASM).
3. Put the ti83plus.inc file into your TASM folder.
4. Unzip the DevPac8x folder into a subfolder titled "devpac8x" (e.g. C:\ASM\devpac8x).
5. Make another subfolder titled "Programs" (e.g. C:\ASM\Programs). This folder will be where you put all your programs in.
6. Install the TI SDK.
7. You need to open Notepad and type the following text in:

@echo off
echo Compiling...
move %1.z80 ..\tasm
cd ..\tasm
tasm -t80 -i -b %1.z80 %1.bin
move %1.z80 ..\programs
move %1.bin ..\devpac8x
cd ..\devpac8x
devpac8x %1
move %1.bin ..\programs
move %1.8xp ..\programs
cd ..\programs
echo Done!

Save this as "compile.bat" into your Programs folder. And finally you need to make sure you know how to operate the link and turn on your calculator...

That is all you need to get started!

Also see Alternate Methods. The above instructions do not work on an x64 bit architecture.