You can categorize opportunities in different types according to your requirements by following these easy steps:
Step 1: Select 'New Type'

On ribbon, click the "Opportunity" tab.
Under Opportunities group, select "New Type".
Step 2: Enter Type Name

Enter name for this new opportunity type. This is required field. You can also select this type as default type whenever you create a new opportunity.
Step 3: Click 'Save & Close'
When you have finished to enter all the desired info, to save this data, choose any one option on ribbon:
Save and Close: saves everything you have entered so far and closes the form
Save and New: saves everything you have entered so far and reopens a blank form for another entry.