We can use the Umbraco.Content() member function in order to get the node by it's id.
var MyContent = Umbraco.Content(1111);
The previous line of code works in a View but if we want to get the nodeĀ in a class then we have to use the following code snippet.
var umbracoHelper = new Umbraco.Web.UmbracoHelper(Umbraco.Web.UmbracoContext.Current);
IPublishedContent MyContent = umbracoHelper.TypedContent(1111);