Windows 7: RJ 45

How can I make my laptop act as a router And share my wifi internet access through the RJ45 port?

Hi and welcome to the Forum.
I can't see how this is possible. Why do you need to do it? Does your existing wireless connection come via a router or do you use a mobile dongle? If the latter then I can't see how you can run more than one laptop at a time!
Completing your system specs would help us to help you more

Could you please go into details on why and how you are currently set up?

Have a look at this:

Using ICS (Internet Connection Sharing)