主语：he
谓语：had been allowed to send a a fax
状语：at last
定语从句：in which he informed the editor that he had been arrested while counting the 1084 steps leading to the fifteen-foot wall which surrounded the president's palace.修饰先行词fax.
在这个定语从句中又有一个宾语从句：that he had been arrested while counting the 1084 steps leading to the fifteen-foot wall which surrounded the president's palace.
在这个宾语从句中又有一个时间状语：while counting the 1084 steps leading to the fifteen-foot wall which surrounded the president's palace.
在这个时间状语中又有一个定语：leading to the fifteen-foot wall which surrounded the president's palace.修饰 the 1084 steps .
在这个定语中又有一个定语从句：which surrounded the president's palace.修饰 the fifteen-foot wall.