Integrating CiviCRM in Wordpress
As ErikH said you do have several questions here. I would suggest taking a look at the following links to the User Guide. This will help clear up the process for you.

Defining Member Types: https://docs.civicrm.org/user/en/latest/membership/defining-memberships/
Membership Sign up: https://docs.civicrm.org/user/en/latest/membership/online-membership-sign-up/

You should also look at the following as these are involved in creating online member signups:

Profiles: https://docs.civicrm.org/user/en/latest/organising-your-data/profiles/

Price Sets: https://docs.civicrm.org/user/en/latest/events/complex-event-fees/#price-sets

You may also need to utilize a few WordPress plugins to achieve what you are looking for. If you have more specific questions please post here.

Hope this helps!