DazzaL has highlighted the nub of the problem but to give a bit more background, on the assumption you're fairly new to Oracle...
create table syntax shows that your command is trying to create a table called
INNERTABLE in the schema
HOMEWORK1. Schema and user are essentially interchangeable in Oracle, so the error saying 'user does not exist' is referring to the
HOMEWORK1 schema/user. Unless you've already created that in your database, that won't exist by default.
You can either (a) create the
HOMEWORK1 user, (b) update the script to replace
HOMEWORK1 with a (non-built-in; see below) user that does exist, or (c) update the script to remove the schema reference which will cause objects to be created as the user you're logged in as.
But who you are logged in as is something to check - it isn't clear from the question, so apologies if you know this and it isn't relevant to you. It's important not to create your own objects under Oracle's built-in schemas, especially
SYSTEM as you could do a lot of damage, and you should not be logged in to a built-in schema routinely - only for specific activities that can't be done otherwise (like shutdown). The only exceptions to that are maybe the sample
SCOTT schemas, and even then it'll be better in the long term to use your own account for anything except queries against those.
If this is a fresh install and you're logging in as
SYS because that's all you had available, please create a new user, assign it the relevant privileges, and do all further work under that.