how do you get a clan to get active

Get members of course..

so the members dont need to be active on fourms or sumthin like this?

You need forum active member

Clans are counted as dead when nobody posts for a long time.
Therefore, if you want a clan to become active, get forum active members(as mentioned by other ppl above) and they have to post a lot.

Ingame doesn't count.

These are what i know.