What should I do to get my guineas to trust me?

I just got a guinea pig two weeks ago. And now I jus got her a new playmate. But the new one is bigger. They both seem to get along but mine first one is very skiddish and my new one is skiddish and I'm trying to get them to trust me. I just took out the hideaway like someone suggested to do so. They said for 15 minutes and iam. But what should I do? My first one won't eat strawberries or anything like that. And idk about the new one since I got her yesterday. Bit it's just hay and guinea pig store bought food . And skiddish. Please help me!