The steps below outline how to purchase IOTA Tokens on a windows platform.
Go to http://iotatoken.io/
Access the wallet client download page by clicking on the following button
On the following page, click on the Download button to download and install the client
Once the client is installed, start the client select Lite version
Generate the seed using the following site: https://iotaseed.io/ , and paste it in the Seed / Password prompt on the client as shown above.
Once your Seed / Password has been accepted you will see
To receive IOTA into your wallet generate an address by clicking on Receive.
This will generate an address, then click on Attach to Tangle, this ensures that your address gets registered in the IOTA ledger. If it fails, try again, once successful you will see
Now you are ready to purchase IOTA from the exchange of your choice and use the receiving address you just created.