First you should know what court you want to edit^^
Look in your NBA live Folder\sgsm\stadia and then choose the court you want to edit
(e.g. clev.viv --> QuickenLoansArena) And do a backup of it
Use Biggui (download at nba-live.com) to open the .viv file
Extract all files to an temporary folder (you dont need all files tough)
Open the .fsh files with fshx (download at nba-live.com)
I dont know everyything about courts so I cant say you exactlywich file to open
However If you found the suitable file you have to extract them , You will have a dds file now
Open them with a Photshop or something like that (youll need a ddsd plugin)
Edit the file to your taste and then again import it to the same file
SAve the fsh file and put it into the sgsm folder
Hope I could help