First, you did not indicate whether you had someone professionally hone the razor to start. If not, I would suggest that you have that done.
Next, I would recommend a WTG pass and two Across the grain (XTG) passes before you attempt to go against the grain.
As for the razor burn, there could be lots of causes but beard prep or technique are the most likely. Make sure that your face is really hydrated from a hot shower or hot towels and potentially a bit of hair conditioner on your beard.
Personally, I would forego the against the grain pass in favor of some touch up going across the grain. This is much easier on your face when you are learning. Some folks find that using good technique, they do not even need to use an ATG pass and just stick with WTG and XTG passes. While I have a heavy beard, I only shave against the grain on my cheeks.
As with everything, YMMV and all that...
Good luck and keep asking questions.