When you are playing with sharepoint first you have to create a web application to play with.Let see how we can create a webapplication in sharepoint
Step1 . Goto Sharepoint Central Admin Site
Step 2 . Goto Application Management Tab
Step 3. Click on Create or Extend Web Application Link
Step 4. Click on Create New WebApplication
In the web application creation you have to specify the different details for your Convenience.
Step 6 . Specify the port above 1500 (You can specify some port number which is easy to remeber.
Step 7 . Specify the Application Pool Name .Give some meaning full name so you can identify your application Poll easily.
Step 8. Specify the user name and password under which Application Pool is going to run(Try to Use windows Service User).
Step 9. Specify the Content DB name so you easily identify your content DB for the specific web application.By Default it will give some junk name
Step 10. Specify authentication Mode in which you want to communicate with Database.You can go for windows authentication (uses the application pool identity use) or you can specify the specific Sql Server user name and password.
Step 11. Submit the Web application creation form.
step 12 . You will see the above screen if it is successfully created.
You can see how to create a site collection in my Blog How to create site collection