Can I get sued for using a picture I took online and edited?

You cannot use other people's creative works without permission. Whether you could get sued depends on whether the owner of the rights in the work gave authorization for people to use his/her work. Here you have copied and made a derivative work of someone's else's picture. Someone owns the copyright in that picture which includes the right to make copies and make derivative works. Sometimes people indicate that the work can be freely used by others, such as on a stock photo site, but that is rarely the case. You should consider getting a photograph you know that you have permission to use.