configuring cisco 873 router

I am new to router configuration but think i have done enough for my system to work.

1. My internal(LAN) network has a network ip of 10.10.1.x.

2. My isp has a router with interface 10.10.10.1. I configure my cisco 873 router to have a wan interface of 10.10.10.2 and corresponding lan of 10.10.1.1

3. The problem is i cannot ping my ISP’s ip but my isp can hit both of my router interfaces.

4. In addition, i can hit both router interfaces from my Lan.

What i’m i not doing right?