What level do you have to be to get into a raid on wow

This depends on the raid in question. Classic raids (such as Molten Core and Blackwing Lair) need a level of at least 60 (although there are reports you can enter them at 58 already).

Raids from TBC, such as The Eye, Mount Hyjal or Gruul's Lair require you to be level 70 or up.

Raids from Wrath of the Lich King, such as Naxxramas and Ulduar, require you to be level 80.

You can check WoWHead, Wowwiki or similar resources to find out the level requirement for each raid.