Hello network experts,
I am new on this forum and i would like to ask if somebody have experience with ISP network architecture. I want to simulate real network situation as you can see in screenshot but I have some problems with routing or NAT configuration or something

Situation is as follows:
I have leased some rack space in hosting center for my servers. Provider assigned me two IP address ranges.
One is 90.183.231.53/30 for outside interface of my PIX and second range is 88.103.247.209/28 which represents NAT pool for my servers.
When I want to make some server available for internet users (e.g. web server) so I configure static NAT for example 192.168.8.165 --> 88.103.247.210 on my PIX. Of course also some additional rules enabling specific ports (TCP 80,443) and so on.
So when internet user want to acccess my specific server he go to IP e.g. 88.103.247.210:80 but through outside interface with IP 90.183.231.53.
And there it is not clear for me how ISP router or something is configured? My PIX is connected just via one ethernet cable somewhere to ISP router or another active component and I don't know how.
I tried to simulate this scenario in GNS3 and I was not successfull (see attached screenshot)
Could someone explain me please how to configure ISP router (in this case R0) to be able route both different ranges via one interface to another different network?
I think it is like small internet or ISP scenario. Could be useful fo more people

Thank you for help.
Jan