I have 7 standlone access points, is it right that i need to use on of this ap like central server,
Depending on the model of your WAP you can either deploy these WAPs as "standalone" (aka autonomous) or controller-based (aka CAPWAP/LWAP or lightweight).
also if i dont have dhcp server, can i use this central ap like dhcp server?
Use a switch. You get more features.