2 Routers (cannot forward ports)

Hello guys! I'm new here... never thought that one day I'm going to register here...

Anyway, I have a problem... I have Two routers one is Main Router/Modem other is second router for wi-fi (since main router accidently lost it's antenna) so let's see:

1st Main Router (Pirelli DRG - A125G)
2nd Router (TP-Link TL-WR740n)

My Computer is connected to 2nd router so I get like this : Computer -> 2nd R -> 1st Main R -> Internet.
Internet is working with no problems at all... But since last week I have to use some Ports... like three of them. This was my first time I ever experienced port opening (or forwarding) issues... I never thought I could be pain in the ***...

to Shorten you answers to most correct ones I'll describe what settings are used now, and still no port forwarding...

My PC IP:
Ipconfig says:

IPv4 Address. . . . . . . . . . . : 192.168.0.100 THIS ONE RIGHT?
Subnet Mask . . . . . . . . . . . : 255.255.255.0
Default Gateway . . . . . . . . . : 192.168.0.1


My 2nd Router IP:
Wan: (not sure what that means anyway)
IP Address: 192.168.1.100 Dynamic IP
Subnet Mask: 255.255.255.0
Default Gateway: 192.168.1.254
DNS Server: 192.168.1.254 , 0.0.0.0


Lan:
IP Address: 192.168.0.1
Subnet Mask: 255.255.255.0


My 1St Main Router IP:
and... erm... I cannot find all these ips.... way more confusing interface than TP-Links...
so thats where my knowledge ends... :(
anyway as you can see from 2nd routers default gateway that my Main router's IP is 192.168.1.254.

So... Can anyone help me to fix this problem.?

BTW: Port forwarding should go like this? Main router should forward to second router, and second router should forward to my pc?