た-Form CLAUSE1 + 後で + CLAUSE2 as “After C1, C2”
This grammar construct is used to convey that the contents of CLAUSE2 occur after the contents of CLAUSE1; in this pattern, CLAUSE1 is conjugated into the た-Form regardless of what form CLAUSE2 is respectively conjugated into. The particle で can be and is commonly omitted.
Hon o yonda ato de nemashita.
(After I read the book, I went to sleep.)
Tabeta ato de ha o migaita.
(After eating, I brushed my teeth.)
This grammar construct can also be used with NOUN + の後で in lieu of a CLAUSE with a predicate in た-Form, in which NOUN denotes an activity or an event.
Bangohan no ato de nemuku narimashita.
(After dinner, I became sleepy.)
Jyugyou no ato de gakushuu juku ni ikimashita.
(After class, I went to evening cram school.)