While nowadays FE7 isn't the best game to start with, it at least has a decent tutorial mode known as the 1st 10 or so chapters, due to it being the 1st game in the series released overseas.
some tips, never use dorcas, only premote at the level cap, use Marcus only as a meatshield, and there is no shame in looking up the means to unlock the bonus chapters
and if you really get discouraged but the game, play sacred stones, the game allows level grinding and the levels are generally easier