Hi and welcome to the forum @disnotyourmail 
If you have a read of The Great Big Review and Testing Guide that should tell you all about becoming a tester 
Any questions can be popped in the Sex Toy Tester - Chit-Chat topic where an experienced tester will usually respond
My top tips are make sure your reviews are well written and have patience because there are a lot more people wanting to test than there are products! 