Looking for a cracker to teach me how to crack

If you want to learn it without using a program such as Sentry, I suggest you learn about HTTP requests, especially POST, and some programming theory. All cracking really is, is iterating over a combolist, sending a login request, and returning the combos that worked. Although, there are usually a lot of obstacles, such as blocking your IP after too many requests, csrf tokens, and captcha. Of course, you can get around all of that pretty easily.

If you want me to point you in the right direction and give you some good resources, just go ahead and PM me. No need to pay someone for this.