Dear Cyrille,
the input
Table[Solve[x^2 + m x == 0.2, x], {m, 0, 1, 0.1}]
gives
{{{x -> -0.447214}, {x -> 0.447214}},
{{x -> -0.5}, {x -> 0.4}},
{{x -> -0.558258}, {x -> 0.358258}},
{{x -> -0.621699}, {x -> 0.321699}},
{{x -> -0.689898}, {x -> 0.289898}},
{{x -> -0.762348}, {x -> 0.262348}},
{{x -> -0.838516}, {x -> 0.238516}},
{{x -> -0.917891}, {x -> 0.217891}},
{{x -> -1.}, {x -> 0.2}},
{{x -> -1.08443}, {x -> 0.184429}},
{{x -> -1.17082}, {x -> 0.17082}}}
If you prefer the Do command, this seems to work:
Do[Print[Solve[x^2 + m x == 0.2, x]], {m, 0, 1, 0.1}]
Is that what you want?
Cheers,
Marco