In a batch file, %cd% is the most commonly used command for the current directory, although you can set your own variable:
set mypath=%cd%
echo %mypath% (where %mypath% is the current directory that the batch file is sitting in)
So say you were wanting to open Myprog.exe. If it was in the same folder, you would use the command:
start %mypath%\Myprog.exe
That would open Myprog from the current folder.
The other option is to make a directory in C: called AutomatePrograms. Then, you transfer your files to that folder then you can open them using the following command:
start "" "C:\AutomatePrograms\Myprog1.exe"
start "" "C:\AutomatePrograms\Myprog2.exe"
start "" "C:\AutomatePrograms\Myprog3.exe"