How I have to form sentences in Lithuanian, using "for"?
I have bought this toy for my son
As for me I do not like that
This road is only for bycicles, not for cars

Question

Answer

gotta use the dative case:
nominative case: sūnus
dative case: sūnui

nupirkau kažką sūnui - I bought something for [my] son

Answer

You will also find this site useful
http://www.italki.com/knowledge/page/LEARNING%20LITHUANIAN.htm

Answer

1.Aš nupirkau šį žaisla mano sūnui.
2.  Man  tas nepatinka. 
 3. šitas kelias yra tik dviračiams, ne automobiliams.