What I posted below has some problems

Well, I have done very stupid thing in creating my deathmatch server. Since i had some problems in an earlier installed mod I have put gun game mod on top of the CSDM mod. After that the DM mod also worked fine. If you do the installing according to the below instructions you will get a gun game not a deathmatch server. You can make the below gun game mod a deathmatch but the mod doesn't contain any preset spawn points so you'll be re spawned in the original spawn points. This will be a disadvantage for one side.
To avoid this I recommend coping the preset spawn point configs(whole csdm folder inside configs) from the CSDM mod(You can get this mod from this link I think CSDM core files will be enough if you have already installed amxmod, but if you have not installed it just download the CSDM with AMX and just extract it into the cstrike folder) and pasting it in the configs folder in the amxmodx.
Then put this line inside the gungame.cfg.
spawnmode = preset
Make sure that
gg_dm 1
gg_dm_spawn_random 1
If you do these you will have a gun game deathmatch mod. Which is really cool!!
If you want only deathmatch I think that putting CSDM mod will be enough.
Make sure that gg_dm_spawn_random is "1" otherwise you will spawn in the original spawn points.
Hope this solved the problem.