configuring SMTP on windows 7 for Civicrm
If you want CiviCRM to send email, you'll need a means of delivering them! SMTP is the internet protocol for doing this. Unlike Linux, Windows does not typically include an SMTP service out of the box. That's OK - you probably want to outsource that task to a provider!


Since you're coming from a LAN, it may be that your internet provider offers an SMTP server you may use. This would be suitable for limited mail use, but not suitable for large mailouts. Consult with your ISP to understand their usage policy.
You mention you're on a LAN at an institute. It's possible your institute provides an SMTP service already - your IT support (assuming you aren't the IT support yourself!) may be able to help.
Dedicated SMTP providers (Wiki listing) are your next option.


Some of these offer a free tier (see my comment below). Free service may have some other cost associated, so choose a provider that you trust (they will be delivering your mail!) and can rely on. 
Some of these providers will require a plugin to work well with CiviCRM.

It's possible to use some "regular" mail providers (Google Apps and similar providers) as an SMTP service. Unless this is a development or test instance, I would not recommend this. (Basically, if you depend on the mails being delivered quickly, choose a dedicated service from those above and pay a few bucks.)
Since you're hosting on Windows, you can't use mail() or sendmail options without installing a local Message Transfer Agent (MTA). This probably isn't the right option for you; choose this only if you have experience with managing internet-facing mail servers.