Membership upgrade

Hi. How do upgrade a members membership plan from standard to a pay plan in the back end so that they don't get charged for they upgrade? Thanks for the help.

Admin --> Users --> Members

Select the Member ID link --> Opening up the Member Profile. At the top you'll see "set membership" as well as "featured"

Admin --> Settings --> Membership Levels is were to create Membership Types, Prices, Actions

Thanks. I have the plan set up, I just couldn't find where to upgrade.