To model ionisation of acids you just need to show that strong acids fully break down in water and weak acids such as ethanoic acids partial break down in water (they form a equilibrium)
I.e. HCl(aq) <--> H+(aq) + Cl-(aq) (using balls marked with + and - charges)
CH3COOH (aq) <--> CH3COO-(aq) + H+(aq) (as above and alsp have a 2 balls connected like this ()() marked as CH3COOH to show that only some acids have broken down in water).
Think this the aim of that exercise to show you understanding of the interactions of different acids (weak/strong) when in solution.