You may find some free public WiFi "Hot Spots" where you can connect when away from home. But remember it is free and public, with may users connected. For security I would use a good software firewall on my laptop if I were to connect to a public WiFi network. If you need reliable wireless access when away form home, there are cellular modems available for laptops. But of course Data on the Cellular systems costs $$$.
I guess the term wireless can be confusing considering there are the wireless cell phones which have different attribute then Your wireless home network.
I guess the easiest to explain this is by thinking about Your cordless phone. Your cordless phone enable you to make calls anywhere in Your house (where there is reception) and use the phone as if it was connected to the wall. To do it you need a base station phone that is connected to the wall and have it transmit the phone signal in the house and you need a hand held device to accept those signal. The phone connects only with Your base station (or Your neighbors will share Your phone as well).
Same thing with wireless home network. The router is the base station, in one end its connected to the "wall" on the other hand you have Your laptop or any other network wireless device.
you can connect Your computer anywhere in the house as long as there is reception as if the laptop was connected to the router using a cable.
same idea ....
so just like you can't use Your cordless phone from Your local starbucks, you can't use Your laptop at statbucks with Your home network. All you can do is use Your laptop with the statbucks local network assuming you have permission to it (which sometimes cost $$$)