Spanish endings help?

What are the AR and ER/IR verb endings for the imperfect and preterite tenses? i know the preterite AR endings are: -aba, __?__, -aba, -abamos, -abasteis, -abaron? im pretty sure those are the correct ones for the preterite. i also need to know the endings for ER/IR preterite and AR, ER/IR for the imperfect.