As mentioned above, the only way to find the IP address of a user that originated an email is by checking the email headers. Depending on your email client, there are various ways to look at the header as mentioned in the following article.

http://aruljohn.com/info/howtofindipaddress/

Once you figure out the IP address, you can use a service such as

http://www.geobytes.com/IpLocator.htm?GetLocation

to figure out the vicinity of the IP address. There isn't an easy way to figure out the exact location of an IP address with freely available or even most commercial Geo location tools.

Just to give you a little background on IP addresses, for IPv4, there are certain addresses that are allocated to private networks.
                                                                                 Start                       End                         No. of addresses
24-bit Block (/8 prefix, 1 × A)                              10.0.0.0                 10.255.255.255     16777216
20-bit Block (/12 prefix, 16 × B)                         172.16.0.0             172.31.255.255     1048576
16-bit Block (/16 prefix, 256 × C)                      192.168.0.0           192.168.255.255     65536

Any IP address in these ranges, belong to a private network. Any public IP address originating from a private network, can only be traced to a range of public ip addresses in that network. For instance, 2 different users sitting in a library in a university could potentially have the same public address at various times -- the reason being that a private network dynamically allocates an IP address to a computer.

A router in your home could dynamically assign IP addresses although these are usually in small ranges. You can also change your network settings to a static IP address. For instance, if you want to run a website from your computer, you need to set your IP address to a specific address and then point any DNS authority to your IP address.