NateLaw,
My experiences are all with Electric shifts and the Vacuum control might shift a little different, but either way the shifting sequence on your truck should go like this:
1 Lo
1 Hi
2 Lo
2 Hi
3 Lo
3 Hi
4 Lo
4 Hi
To start off getting used to it, start off in 1 Lo, go thru all the gears and lastly shift to 4 Hi (as Rich has mentioned). This will give you 5 speeds. Once you are familair on how it shifts you can then try downshifting the rear (as described above) then proceed onto "split shifting".
Bill
