Well edit your podbot.cfg and make sure you have pb_min/max bots edited correctly. Than use the command amx_pbmenu
If you want to add more bots use amx_rcon pb_maxbots "number" to edit the maximum bots if more players join. Than use amx_pbmenu to add more bots.
Read because it should give you alot of clues on what to do.
http://podbotmm.bots-united.com/doc_v3/index.html