There are a few books which are useful primers. Two that I have are Observing the Sun: a pocket guide, by J Jenkins andHow to Observe the Sun Safely by Lee MacDonald. However neither give much detail on using a Herschel wedge.
The image through the wedge is very bright and to see detail you will need a filter that will give contrast. I use a Baader Solar continuum filter. Some prefer a polarising filter as the Baader filter gives the Sun a green colour but I also think it shows more detail.
Of course we are now in a period of solar minimum and there have been very few Sunspots to view. This minimum might continue for a while yet so you will have to be patient. As well as sunspots you can also see bright features known as faculae, usually near the solar limb. If the seeing is good it is also possible to see the solar granulation, but this usually takes a bit of experience to achieve.
I eventually took the next step and purchased a dedicated solar Ha scope. This allows you to view the solar chromosphere, the layer above the photosphere you view in WL. There is usually some activity here even when the sun is in its minimum phase. Prominences and filaments are usually viewable. The problem is that this is where solar viewing becomes rather more expensive. Solar scopes and Quark lenses are not cheap, but I think the are worth the money for the extra interesting viewing they allow.