i am selling my business partner my share of the partnership. How do I put a lien on the note paying off the purchase?

If I understand you correctly, your partner is buying out your share of the business.  You will have a promissory note from him setting forth the indebtedness and payment terms, but you want to secure his payment by liens on his assets.  For real property assets, you would have a mortgage lien, for non-real estate assets you would get a U.C.C. lien.  There is documentation connected with either of them (including, of course, your partner's agreement to grant you the security interests), and you would need to register them, but you would need tp speak to a California lawyer to get the particulars of what needs to be done in California.