There are a couple of pages in the wiki about creating a player model...
(
DO NOT LINK) h t t p s : / / openarena . wikia . com/wiki/Making_a_player_model
(
DO NOT LINK) h t t p s : / / openarena . wikia . com/wiki/Creating_a_player_model_in_Blender
But maybe they should be updated/reworked...
(
DO NOT LINK) h t t p s : / / openarena . wikia . com/wiki/MD3_format
(
DO NOT LINK) h t t p s : / / openarena . wikia . com/wiki/DeveloperFAQ#How_do_I_export_md3s_in_Blender.3F
I suppose also searching for some documentation for Q3 may roughly apply to OA, too:
Example for skinning:
http://www.moddb.com/games/quake-iii-arena/tutorials/skinning-for-newbies-part-1