As User10383 pointed out, Dissemination in Derrida should be contrasted with polysemy (among other things). An interpretation is constrained by polysemy if it considers only the various possible discrete meanings a text could have. For example, the two or more meanings of a pun. An interpretation recognizes the possibility of dissemination if it acknowledges as well that anything textual (anything at all) can be put forth without any intention-to-signify whatsoever. In the field of rhetoric this is known as irony. I can say words or perform actions without believing in them or meaning to say anything by them at all.
This marks (or re-marks) the difference between what others have called structuralism and post-structuralism, though Derrida never used the latter term to describe his own work. Structuralism dreamed of creating a combinatorics of all possible meanings of all possible signifiers in order to exhaust the project of interpretation (Levi-Strauss' Mythologiques is probably the best example of this) Derrida shows the impossibility of such a project by noting the essential possibility of dissemination. Because dissemination is an a priori possibility, one can never saturate the context of an interpretation by identifying exactly what is relevant and what is not to the meaning of a particular text.
“Dissemination”, the essay in the eponymous book, is the best source on the subject, though Limited Inc, which includes the essay “Signature, Event, Context” is a bit more approachable. Derrida does not discuss dissemination as explicitly there, but everything he has to say about these three themes - signature, event, and context - relates to dissemination. Here is a citation:
Before elaborating more precisely the inevitable consequences of these nuclear traits of all writing-that is: (1) the break with the horizon of communication as communication of consciousnesses or of presences and as linguistical or semantic transport of the desire to mean what one says [vouloir-dire]; (2) the disengagement of all writing from the semantic or hermeneutic horizons which, inasmuch as they are horizons of meaning, are riven [crever] by writing; (3) the necessity of disengaging from the concept of polysemics what I have elsewhere called dissemination, which is also the concept of writing; (4) the disqualification or the limiting of the concept of context, whether "real" or "linguistic," inasmuch as its rigorous theoretical determination as well as its empirical saturation is rendered impossible or insufficient by writing-I would like to demonstrate that the traits that can be recognized in the classical, narrowly defined concept of writing, are generalizable. They are valid not only for all orders of "signs" and for all languages in general but moreover, beyond semio-linguistic communication, for the entire field of what philosophy would call experience, even the experience of being: the above-mentioned “presence."
Limited Inc p. 8-9
Dissemination is certainly a relevant theme if you are discussing genius. The possibility of an action or work (such as a work of art) purely belonging to an agent and its merit returning to them alone is undermined by dissemination. This is further explained in the essay.