Trying to pull a field from Account section into the Opportunity section

Hello.

First I want to preface this by saying I just inherited the admin role of our CRM due to a sudden departure, and my background is not in running systems/architects. Please keep that in mind with any responses (so the more details in the steps the better).

I have a field on the Account tab which classifies each account into certain types (type 1, type 2, etc). What I have been told to do is have that field/data show up on the opportunity page whenever an opportunity is opened under those accounts. On the opportunity page, the account is selected by clicking on a magnifying glass and selecting the company. So what I would need is some type of way to populate a new field on the opportunity that will show that company x is a type 1 account.