How do I get someone to test my writing skills?

You can join book communities such as Goodreads.
Goodreads has several groups where people will happily review your work. They will usually do so for free. But because Goodreads is community-based, they don't normally like reading books of strangers, so you may need to participate in the Goodreads community somewhat.

You could also join book review groups and author groups on social networks and ask for help.

There are many websites available that allow you to hire proofreaders. For example:

• Fiverr (cheap but limited and amateurs)
• Freelance Alliance (expensive but extensive and professionals)