Could someone please point me in the right direction on where I could find the guidance/instructions in the help section? Is it called something else maybe?
could you explain more what you're trying to do? If it's to truly lay one pattern over another, then you need to have both patterns open and mark to set for copy and paste it over the other. If it's the underlay feature to help you create a pattern, I can't help much because I don't use that feature.
Not quite sure if this is the answer - I will explain more in detail what I am trying to do: I have an outline of a flower. This flower I would like to fill with a repeat pattern (like a pattern fill). Maybe I am thinking wrong, is there another way of doing this?
It sounds like what you want is an underlay -- or a conversion of an image to a pattern.
An underlay just shows the image under the grid and you fill it in. You would actually put in the outline of the stitches for each part and then you can "fill" within that border. But how you get the underlay where you want it and how you want it, I cannot say. I do not use this feature. There is a tutorial. It should help.
Converting an image to a pattern is a different story and always requires a lot of tweaking and changing from the initial import into a pattern from an image.
For both procedures, time is the main component. Both are possible but I don't think it's a quick process.