Fresh manure is too "hot" to go straight onto the ground.
As previously mentioned, let it rot down, give it a year if it is fresh - and ideally when it is black and has no smell with plenty of little red worms in it, then dig it into your soil.
Best time to do this will be early spring, before you plant your potatoes into it.
But don't forget to check the acidity of your soil, and let it reflect in what you plant in it.
For example, I always manure the plot where I am going to plant potatoes as spuds prefer a more acid soil.
For legumes - which should follow your potatoes in the crop rotation, then make sure the soil is up to around 6.5 to 7 ph.
Brassicas should follow the legumes and the soil should be the same. Garden lime will raise the ph for you.
Don't manure the same patch year after year mind!!