When and how do I apply manure to my garden?

Farmyard manure would not be suitable for lawns as its texture would be too coarse. You should use Shamrock Moss Peat by spreading a light layer and brushing this into the grass. You can also add sand to this and spike the lawn as this will help to open heavy clay soils. Alternatively use Growise Enriched Top/Soil as a top dress. Autumn is the best time to do this work just make sure you do it on a good dry day.

For shrubs, yes you can use farmyard manure. Spread a layer several inches deep around the root area and this will act as a mulch and it will also release the nutrients slowly over time. When planting new trees and shrubs use plenty of farmyard manure in the planting hole and with vegetables dig in several inches to the area for planting in spring.