If your campaign has received a large number of donations offline, rather than enter them one by one you can just change the total amount raised and number of donors displayed on your campaign page.
NOTE: You're not actually creating donor records, just changing what's displayed in these boxes:
Sign in to your WeDidIt account and select 'Campaigns' from the left panel. Click on 'Displayed Totals' and select a campaign form the dropdown.
Select the campaign you're adding contributions to and enter the total additional funds raised and total additional donors then click 'Update Totals'.
NOTE: This resets every time you re-enter additional funds raised and additional believers. So if today you have one offline donation from one donor for $100 and tomorrow you get another $100 donation, you would need to enter $200 and 2 additional believers (i.e. you'll need to do the math before entering each new update).