First thing both the PCs should be connected in a network.Like a LAN Network.
Or if you want you can directly connect them with the help of a cross cable available in market for connecting two PCs through ethernet.
And confirm they both communicate with each other by giving an IP address range say 192.168.10.1 for one PC and 192.168.10.2 for the other.Subnet mask will come by default just by clicking on that field that is 255.255.255.0 and leave the gateway field blank for the first computer.The gateway for the second will be the ip of the first will come to this part later.This can be done by right clicking the local area connection clicking status then properties then Internet protocol TCP/IP and properties.
Try ping command for checking the connectivity.
go to START RUN on the first PC type " ping 192.168.10.2 "
You should get a valid replay back from the other PC
Now it's confirmed they are connected.
Then on one first machine where you connect the data card check if you are properly connected to the internet by surfing some sites.
Next you will have to check the DNS address of reliance network for your internet.You can do that in any way like right click on the local area connection of reliance click on status and then support tab in that details.Here you will find a few DNS addresses provided by reliance note them down any two of them.
They will look like starting from 124.124..... or 203.138..... they can be totally different also doesn't matter note them down.
(The other way to find them is go to command prompt type
ipconfig /all here you will see the DNS server addresses).
Also in the advanced Tab of this reliance LAN enable that is check the boxes of sharing internet connection.
Then on the other PC open the local area connection(here it will be only one LAN connection) go to properties then INTERNET PROTOCOL TCP/IP properties and there you have to give the gateway address as the IP address of the first PC(that is connected to internet data card)so that will be 192.168.10.1 as mentioned earlier both PC IP addresses.
And also provide the DNS addresses which you have already written down in the two DNS fields provided.
Now open the internet explorer of the other PC and browse any web site
NOTE: In the internet setting or options you have to select it as NO PROXY or USE SYSTEM PROXY options or Automatic detect system proxy.
And enjoy web surfing on both the PCs.
Any queries comment it here i will reply back .