Download and install XAMPP to your laptop. The XAMPP packages contains a web service (apache), email service (mercury 32), database service (mysql), and FTP service. Basically, everything you could need in one neat little package for a basic setup. Run the XAMPP console and make note of the ports that the services are running. Turn off any service that you don't want. At this point, the only service you probably need is apache. It should be running on port 80. You will need to go into you firewall and make sure that you have a rule for port 80 (plenty of tutorials online that will show you how to do this on your version of windows).
Open your web browser and type in either "localhost" or "127.0.0.1" and you should see "It Works!" If not, then you don't have your firewall configured correctly.
Open a command prompt and type the following and press enter: ipconfig
Under the IPv4 settings you should see 3 IP address. Make note of all 3. The first is the IP address of your computer. The second is the network mask. The third is the gateway address (the address of your router).
The following isn't best practice, but it will get things working for you. You will need to first go into the properties of your network adapter IPv4 properties and change it from dynamic to static. Then manually key in the 3 IP address you noted in the previous step. You will also be forced to manually enter in at least 1 DNS IP address. You can use 4.2.2.1 and/or 8.8.8.8 for the DNS.
Next you will need to open a browser and type in the router IP address. This should take you to the login page for your router. Hopefully you have the login, if not you can google the default logins for most models. Once you are logged in, you will need to create a firewall forwarding rule. Use your IP address of your computer, port 80, TCP.
Now you need to know how to access your server remotely. In your web browser go to "whatismyip.org" and this will display your external IP address. If your router is configured properly, then a friend should be able to enter that IP address into their web browser and also get the "It Works!" page.
In the XAMPP console there's an explore folder button. This will open windows explorer to the xampp folder on your computer. Under apache there should be an "htdocs" folder. You should be able to dump the files you want to share in there and share links to it with your "[external IP address]/filename.ext".
Note that residential ISPs normally rotate your IP address about every 3 months (or sometimes if you power cycle your modem/router). There are ways around it. You can get a domain name for $0.88 on namecheap.com and there are free dynamic DNS services such as afraid.org that will allow you to not worry about the dynamic IP rotation. Setup is pretty easy. You just point your domain name to your current external IP address. Then there's an application that you can install on your server that will check every 5 min to see if your external IP has changed and if so, automatically sends a DNS update records command.
I know this wasn't super specific, but should get you off in the right direction for a first time server setup. You'll also learn some fundamentals about networking along the way.
