How to configure on Mikrotik VLAN provided by the provider?

Question

Computer networks

The company has 1 office and 2 branches, all offices are connected to the same Internet provider. All offices, of course, must be combined due to the availability of servers and the need to access them. The provider has provided the ability to combine at its level through VLANs. After the merging, I sent the following information:
vlan500 was added as a tag on the port towards Branch 1.
vlan600 was added as a tag on the port towards Branch 2.
Please help me understand what to do with this now. I am familiar with vlan only in theory, I have never used it in practice. There are mikrotiks everywhere, both at the provider and in all my 3 offices (1 office and 2 branches), model RB951G-2Hnd.
Let the addresses be:
Branch_1: 100.100.100.1
Branch_2: 100.100.100.2
Office: 100.100.100.3

Answer 1

Branch_1
/interface vlan
add interface={PROVIDER INTERFACE} name=vlan500 vlan-id=500
/ip address
add address=100.100.100.1/24 comment=defconf interface=vlan500 network=100.100.100.0
Further by analogy.
What VLAN was given to the main office?