Well obviously....... But I need it for school, so I need to do it all online.... I'm going to school out of state, but thank you for that great and well thought out answer.....
If you e-filed your tax return, there is no written signature on the tax return. It was signed electronically. The electronic signature cannot be printed and does not appear in the PDF of the tax return. The people in the school's financial office should know this, but we often see that school financial office people are surprisingly ignorant of how tax returns are filed.
The easiest thing to do is to print the page that they want a signature on, sign it, and give them the signed copy. That should satisfy them.
Can you mail the signed form to the school? If not, see if you can find someone with a scanner that you can use. Scan the signed page and send them the scanned file by email, or upload the scanned file to their web site, if that's what you mean by doing it online. An office services store like Staples or FedEx Office might be able to scan a document for you.
Be cautious about sending anything with personal information, such as your Social Security number, by email or uploading to a web site. Email is not secure, and the web site might or might not be secure. If you have to email it, encrypt it if possible. Maybe they will accept a copy with the Social Security number blacked out.