I have a question, it is possible to have two WAN interfaces to configure a cisco 892 router
with an ip 255.255.240.0 188.8.131.52 adderess of the first interface and a different ip address 184.108.40.206 255.255.240.0 on the second interface
Well, the router has two WAN ports (1 x Ge, 1 x Fe), so you can physically do it.
Based on the addressing and subnet masks you've provided, you can't do it in software, because both IP addresses are in the same (huge) subnet, and the router won't let you have two interfaces IP addresses in the same subnet.
So the outright answer, based on the information you've given, is no.
If you have different IP address possibilities (different subnets), you could probably do it - but you wouldn't be able to run any really advanced routing protocols - they will run BGP, but there's no way you coulod get a full routing table into a router that small - OSPF will also work, but it depends how many routes you want to get from upstream.
Moot points if you can't change your IP addresses anyway - you can't have two different interfaces with IP addresses in the same subnet active on a router.