Well done for finishing your book!
Hiring a qualified, experienced proofreader/editor is more expensive than many authors anticipate - but it's usually worth it, because they can make a huge difference to your book. However, if you haven't got any money, then your options are limited.
(There are cheaper proofreaders out there but there's usually a reason why they're cheaper: they're new, they're less qualified, they're not very good.)
Why do you think you'll make money on your book? Most authors don't.
You have two options:
self publishing
try to find an agent.
If you choose the latter, get a copy of the Writers' and Artists' Yearbook and search for agents in that.
If the former, then you need to bone up on your self publishing options. Do you want printed books/e-books? You'll need to decide on a market for your book then market it yourself using social media. You'll need a book cover, ISBN, etc too. But first your book will have to be as polished as possible, and that means editing and proofreading... Or you'll get bad reviews.
There are plenty of sites that give advice on self publishing - just do some googling and decide which route you'd prefer to take.
What genre is it? It's short for a book - in between a novella and novel.
Don't pay to have it edited or proofed: you're very unlikely to make that money back, and it's difficult to find good-quality services so you can't guarantee the person doing the work will do a good job.
It's not difficult at all, On the rise. Go to the Society for Editors and Proofreaders website (www.sfep.org.uk) and check out their Directory of Editorial Services at www.sfep.org.uk/directory
SfEP is the UK's professional organisation for proofreaders and editors. You have to be a Professional Member of the Society to have a Directory entry, so quality and experience are guaranteed.
Type in any key words - eg fiction, romance - and then check out the editors who are listed.
(I'm a copy-editor with 20 years' experience. I work for both self publishing authors and published ones.)