1. label your turtle
type: label set MyTurtleIsCalledThis
This will do two things for you. Your turtle can be picked up and moved and it wont forget what programs you taught it
It will also preserve its fuel level when you pick up your turtle.
2. type: edit startup
You're now editing a program called startup. The turtle runs startup whenever the chuck it is in is loaded.
type: shell.run("TheNameOfTheProgramYouWantTheTurtleToRunWhenItIsLoaded")
hit the ctrl key
save the program
hit the ctrl key and exit
You can now run the program by typing startup or the name of the program you want it to run.
It will now run each time the turtle's chunk is loaded. Hope that helps.
PS: Instead of 2 being a shell.run command to run your program you could just type your program into startup and have the same result.