How to set membership lever for users in the process of registration?

I am a newbie about wordpress, and I am facing a problem about s2Member. The problem is I want to use the membership level to restrict the users’ access. But I don’t know how to give membership level to users when they are registering. I set a check box in the registration form, and I’d like to set the users who check it with higher level. How can I implement it? Thanks!

Are your members going to be paying or not? If they are going to be paying, which payment processor are you going to be using?

No, they are not going to be paying.

The free version of s2Member uses the regular WP registration form, which will set users who register at level 0.

If you want to have multiple free levels, you will need the Pro version of s2Member, which comes with its own forms, which you can customize for as many different levels as you wish.