Cross the stream (Deepdale Gill) just up from where it intersects into Walden Beck. on the 3D image the Red route shows the suggested route and the blue route is the dotted outdooractive map trail.
After crossing the stream bear right and start heading uphill through Walden Moor. The path here can be indistinct and hard to follow - Check the 3D image for an overview - you can see the path lines going up Walden Moor just to side of the red arrow. there may be more than one path where various hikers have opted to walk through the moor. As you ascend, find the most suitable path for yourself - as long as you keep to the general path line of Macs App and the dotted trail you shouldn't have any problems at all!