Not much to it. Basically you get blocks in your code that will only run if a condition is met (e.g. the surrounding if/endif statements). Every time you have an if, you indent one tab with the tab key on the following line. Every time you hit an endif, you delete the tab. This allows you to see the conditional code quickly by the presence of the tab, and allows you to quickly see all the ifs/endifs are paired.
if (a>1)
apple=2
print "apple"
endif
for x=1 to 5
print x
if (x>3)
print "X bigger than 3"
endif
next
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