With that type of plow the usual set-up for pushing forward would be to have the plow frame parallel to the road surface. That way when you angle left or right the cutting edge stays flat on the ground. If your frame is not parallel to the road when you angle one corner of the blade will lift and the other will dig in unless the plow is built with ability for the blade to rotate which I can't see. Look at McMxi's photo above in post 23,991 and notice how the plow frame is parallel to his road.Not a lot of snow but enough to start learning with this thing (from Homestead).
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It is tough to plow unfrozen gravel for anybody, even a veteran, so don't feel bad if you struggle to learn. If the gravel is unfrozen you want to keep the blade up off the surface a little which isn't easy. Plow shoes of ample size can help a lot with that. To start I would do the best I could w/o digging up gravel and then back drag it to make it even and better looking, like you were doing. If you are turning up gravel try to keep it on the drive, like plowing narrower, so that in the spring it is easy to reclaim. It looks like a nice plow - hope you enjoy it.
gg