Hi,
As i have 8 No. cAP ac devices to setup on a network. i want to know if it is possible to put them all on single loop using the second Ether2 PoE out. if yes, then how can i configure the second interface to continue with the trunk forwarding all the vlans coming in from the Ether1.

Answered here......
viewtopic.php?f=2&t=170991&p=836880#p836880

As for vlans, use this guide......
viewtopic.php?f=13&t=143620

@anav doesn't want to discourage you ... but in short: cAP ac can power one, possibly two, cAP acs via PoE out. The prerequisite for even trying to power two additional units is to use 48V power adapter (the supplied PA is 24V and can power one additional unit powered via PoE out of the fist one). But not more than that, PoE out port has limitation of 400mA and at 48V that's a bit more than 19W while rated power consumption of one cAP ac is 13W (up to 24W with attachments, which probably include PoEout powered gadgets).

Thank you for all your guide, however. i was previously on Ubiquiti AP, and my familiarity with how to trunk multiple vlans to its LAN interface without any configuration to pass to the WLAN let me have Point to Point Network with vlans passing directly to the AP-Lite. but now am face with different Device (Mikrotik) so i need help on : do i configure brigde to pass all the VLANS traffic from Eth1 to WLANS and finally to Eth2 that passes further to the second cAP ac? or is there anyway of doing it?

Thanks for your responds please.

Yes create single bridge on the capac, the eth2 to the second CAPAC is also a trunk port, as eth2 accepting the vlans from the router.
The guide for vlan setup on bridge was already provided.