Well, in When the Wind Blows, you have to think about what techniques Briggs uses in order to influence the reader politically, socially and economically. From my recollection of reading the text, it is clear that first and foremost Briggs is trying to evoke an anti-war sentiment out of the reader (this can be seen by how the readers witness the two protagonists declining from radiation sickness).
The fact that When the Wind Blows is a graphic novel means that Briggs will be intending to influence readers through predominantly visual means, as well as the dialogue from the readers. In a way, the two protagonists are the ideal victims as they are innocent and working class (?) aged citizens — this is the type of demographic readers would be able to relate to rather easily, both politically and socially. Not to mention presenting an old, long-married couple is even more ideal when it comes to inspiring pity and sympathy from the readers.
As for the dialogue, throughout the text the readers witness the two protagonists being time and time again oblivious to the horrors occurring around them: reminiscing about the Second World War prevents them from seeing the reality of war itself; they misread the advice given in the pamphlets; they unknowingly smell the burning corpses of their neighbours and they exhibit confusion to the progressive degradation of their physical states. Like I said before, Briggs makes sure to epitomise the innocence of these two protagonists, because it would best bring out sadness for the victims (social aspect) and anger against war (political aspect).
I am not too sure what you can mention in terms of economical aspects and my memory of the text is rather faint. If you can find references to the two protagonists' economic status (e.g. talking about their occupations or the declining resources as they remain in their house), this can be used for answering how the text positions the reader economically. If these two protagonists are in working class, you could say something along the lines of how the government tends to neglect the working class and this is further emphasised as irony while they die, since their continual faith in the government is communicated many times.