Madden NFL 12 does not have a “Create a Team” mode in the modern sense (custom logos, uniforms, stadiums, full roster editing). That feature existed in Madden NFL 09 and 10 but was removed for 11 and 12.
Relocation (moving team, new name/logo/uniform) returned in Madden 25 (2014). Not available in 12.
Bottom Line: For true create-a-team (logos, unis, stadium), play Madden 10 (last with full feature) or Madden 25+ (relocation). Madden 12 limits you to roster manipulation.