Today the book showed me how verbs are written and what their endings are. It says all verbs end in -en, and a small number end in -n, but it gave the example sagen and a list of conjunctions like ich sage, du sagst, Sie sagen etc. I'm wondering why if all verbs end in -en, some are ending in just -e, or -t or -st? It didn't explain why that is. That is just a bit confusing to me

Then there's the verbs that add an -e when the stem of the verb ends in -m, -n, -d, or -t before the ending in the du, er/sie/es and ihr constructions. That had a decent explanation of why the -e was added because how would you pronounce say atmest without the "e". Still a little confusing but that seemed to have a better explanation.