use of mostly

[Carvalho]

Can we say mostly or should we say speacially?
mostly children show their pictures on the net.

[Mister Micawber]

Not 'mostly' the way you have structured your sentence, which is quite unclear. Do you mean 'most children show their pictures on the internet' or 'it is mostly children who show their pictures on the internet' or 'children show their pictures mostly on the internet'?
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Native English teacher at Mister Micawber's

[Carvalho]

ok, thanks to your examples I can see how the sentence should be structured.