You may get very good hints for the folllowing, good luck:
sysuse auto, clear
encode make,gen(make_n)
codebook make_n //find the unique values (74),which will be used in the following "xlabel()"
twoway (bar mpg make_n if foreign==0,barwidth(0.5)) ///
(bar mpg make_n if foreign==1,barwidth(0.5)) ///
(line price make_n, sort yaxis(2)), ///
legend(order(1 "Domestic" 2 "Foreign" 3 "Price")) ///
ylabel(0(50)200,axis(1)) ///
ylabel(0(4000)16000,axis(2)) ///
xtitle("") ///
xlabel(#74, labsize(tiny) angle(vertical) valuelabel)